Here is how I did this... Create a sfGuardAuth module in your application and edit the actions.class.php file as follow.

The trick is to not try to overwrite the sfGuardAuth/signin action, as it use validation. As well it allow you to use the "normal" signin way (form and etc).

require_once(sfConfig::get('sf_plugins_dir').'/sfGuardPlugin/modules/sfGuardAuth/lib/BasesfGuardAuthActions.class.php');
 
class sfGuardAuthActions extends BasesfGuardAuthActions
{
  public function executeHTTPSignin()
  {
    // get somme interesting stuff!
    $request = $this->getRequest();
    $response = $this->getResponse();
    $user = $this->getUser();
 
    // An HTTP authenticated user cannot logout (browser always send authentification datas)
    // So we must be sure that the user has seen the HTTP authentification box before
    if ( $user->getAttribute('request_authentification') )
    {
      // If authentification datas has been sent
      if ( isset( $_SERVER['PHP_AUTH_USER'], $_SERVER['PHP_AUTH_PW'] ) )
      {
        // If correct username given
        $guarduser = sfGuardUserPeer::retrieveByUserName( $_SERVER['PHP_AUTH_USER'] );
        if ( $guarduser instanceof sfGuardUser )
        {
          // If correct Password given
          if ( ($guarduser instanceof sfGuardUser) and ($guarduser->checkpassword( $_SERVER['PHP_AUTH_PW'] )) )
          {
            // we can signin the user and redirect it
            $user->signin( $guarduser );
            $user->setAttribute('request_authentification',false);
            $this->redirect( sfConfig::get('app_sf_guard_plugin_success_signin_url','@homepage') );
            throw new sfStopException;
          }
        }
      }
    }
 
    // else, popup the authentification box
    $user->setAttribute('request_authentification',true);
    $response->setHttpHeader( 'WWW-Authenticate', 'Basic realm="Identification"' );
    $response->setHttpHeader( 'HTTP/1.0', '401 Unauthorized' );
 
    // This will be displayed if the user cancel the authentification process
    $this->forward( 'sfGuardAuth', 'password' );
    throw new sfStopException;
  }
 
  public function executePasswowd()
  {
    # Implement this action as usual...
  }
}
 

Enjoy... (I hope)

Sometimes if you use sfGuardUser and sfGuardUserProfile you need to create an empty profile just after adding the new user (automating is such a great thing). This snippet will help out.

UPDATE: Will Killian pointed me to the solution of using this without touching the plugin files, this way it will still work after upgrading the plugin. Thanks!

Edit apps/backend/modules/sfGuardUser/actions/actions.class.php

(create directories and files as needed, just for the record I use this with admin generator on "backend" app)

Mine looks like this.

<?php
 
require_once(sfConfig::get('sf_plugins_dir').'/sfGuardPlugin/modules/sfGuardUser/lib/BasesfGuardUserActions.class.php');
 
class sfGuardUserActions extends BasesfGuardUserActions
{
  protected function savesfGuardUser($sf_guard_user)
  {
    parent::savesfGuardUser($sf_guard_user);
    $user_id = $sf_guard_user->getId();
    $c = new Criteria();
    $c->add(sfGuardUserProfilePeer::USER_ID,$user_id);
    $profile = sfGuardUserProfilePeer::doSelectOne($c);
    if(!$profile) {
      $profile = new sfGuardUserProfile();
      $profile->setUserId($user_id);
      $profile->save();
    }
  }
}
 

or apply transformation on sfGuard tables into your main schema

Problem

When you generate a schema with sf_guard tables from your main database with the following command, the schema contains all the tables included the sf_guard tables (it's normal).

symfony propel-build-schema xml
 

Then after, when you build the model classes, the sfGuardPlugin classes have a wrong name and are in a wrong place (lib/). There is a post on this problem, how to correctly use propel-build-schema after sfGuardPlugin installation?

symfony propel-build-model
 

Solution

To correct the schema, apply the transformation on the XML schema after the schema generation :

symfony transform-schema-sfguard xml
 

The script add in the schema for all sf_guard_* tables, the package and the phpName with the camelcase used by the plugin.

Also you have to switch off the schema in the plugin to don't have twice declaration :

mv ./plugins/sfGuardPlugin/config/schema.yml ./plugins/sfGuardPlugin/config/schema.yml.off
 

The script: myPakeTransformSchemaSfguard.php

pake_desc( 'apply transformation on sfGuard tables into your main schema' );
pake_task( 'transform-schema-sfguard', 'project_exists' );
 
function run_transform_schema_sfguard($task, $args) 
{
  // Check params
  // -- missing params ?
  if ( !count($args) > 1 ) {
    throw new Exception("You must provide a transformation to apply.\nsymfony transform-schema-sfguard\nsymfony transform-schema-sfguard xml");
  }
 
  // -- schema exists ?
  if ($args[0] == 'xml')
  {
    $schema_filename = sprintf( '%s/schema.xml', sfConfig::get('sf_config_dir') );
    if ( !file_exists($schema_filename) ) {
        throw new Exception( "Missing schema.xml" );
    }
  }
  else
  {
    $schema_filename = sprintf( '%s/schema.yml', sfConfig::get('sf_config_dir') );
    if ( !file_exists($schema_filename) ) {
        throw new Exception( "Missing schema.yml (not yet implemented)" );
    } else {
        throw new Exception( "schema.yml not yet implemented" );
    }
  }
 
  // Backup schema
  //pake_copy( $schema_filename, $schema_filename . '.previous', array('override' => true) );
 
 
  if ($args[0] == 'xml')
  {
    $handle = fopen($schema_filename, "r");
 
    // get the entire file in $contents
    $contents = '';
    while (!feof($handle))
    {
      $contents.= fread($handle, 8192);
    }
    fclose($handle);
 
    $num = preg_match_all('/<table(.*)>/i', $contents, $matches);
 
    // each table definition found
    foreach ($matches[0] as $val)
    {
      if (!preg_match('/package|phpName/i', $val) && preg_match('/name="(sf_guard_.+?)"/i', $val, $val_matches)) {
 
        $table_name = $val_matches[1];
 
        //$php_name   = sfInflector::camelize($val_matches[1]);
        $php_name = sfToolkit::pregtr($val_matches[1], array('#/(.?)#e'   => "'::'.strtoupper('\\1')",
                                                             '/(_)(.)/e'  => "strtoupper('\\2')",
                                                             '/(^)(.)/e'  => "strtolower('\\2')"));
 
        $pattern    = '/(<table.*)(name="'.$table_name.'")(.*>)/i';
        $replace    = '$1$2 package="plugins.sfGuardPlugin.lib.model" phpName="'.$php_name.'" $3';
        $contents   = preg_replace($pattern, $replace, $contents, 1, $count);
 
        pake_echo($table_name);
      } 
    }
 
    // write the result
    $handle = fopen($schema_filename, "w+");
    fwrite($handle, $contents);
    fclose($handle);
  }
}
 

Installation

Put the myPakeTransformSchemaSfguard.php script into data/tasks directory

Use

mv ./plugins/sfGuardPlugin/config/schema.yml ./plugins/sfGuardPlugin/config/schema.yml.off
 
symfony propel-build-schema xml
 
symfony transform-schema-sfguard xml
 
symfony propel-build-model
 

If you want add a column to sfGuardUserProfile's list view for show a link to sfGuardUser's edit view:

Create a partial : site.com/apps/backend/modules/sf_Guard_User_Profile/templates/_user.php

And put this:

<?php echo link_to($sf_guard_user_profile->getSfGuardUser()->getUsername(), 'sfGuardUser/edit?id='.$sf_guard_user_profile->getSfGuardUser()->getId()) ?>

PD(It's not very much, but it is my first snippet)