PayPal & IPN

[yelwor]

Right, I'm working on a module to combine FEUsers, Cataloger and PayPal.  I'm 95% there and was wondering if anyone could advise me on a way to create a db connection from a php file not within CMS to the mysql db that CMS is installed on.

If anyone knows how PayPal works they'll understand me when I talk about IPNs.  When PayPal has completed a payment from a customer it can be configured to return all the details of the transaction back to you in a post to a php file that would then write that data to the db.  So, I need to know how to open a db connection to the mysql db using the username and password in the config.php file to make things simpler for people when installing my module.

Your help would be much appreciated.

Cheers

Phil