I've taken the scripts available from http://tools.have2.com/propel/DBDesigner2Propel.php and created a downloadable package to use locally.

Just extract the files into a web accessible area and point to the DBDesigner2Propel.php file. It should work out of box without configuration provide you are using the default PHP5 php.ini

This downloaded version also includes a new field for declaring the new plugin package name for developing plugins.

For example
{{{
<table package="plugins.sfGuardPlugin.lib.model">
}}}

 * Now you can use the sfDB4toPropelPlugin
   * http://www.symfony-project.org/plugins/sfDB4toPropelPlugin
   * http://www.strangebuzz.com/index.php/2008/09/09/36-new-symfony-11-plugin-tutorial-sfdb4topropelplugin