Bidder Role in Portal

Dear Experts,

Scenario:

A supplier registers himself in the SAP SUS system(1) using a Webdynpro Page. After successful registration, a user ID is created automatically in SAP SRM system (2). We use Enterprise portal system (3) as a collaboration tool to show SRM and SUS system. Enterprise Portal uses the UME & is connected to the SRM system. As the user ID is already created SRM system, the supplier will try to login to the Enterprise Portal system. But as there is no portal roles assigned to the Enterprise Portal system, he will get the error "No portal Roles Assigned. Inform system administration".

Please note that there are three systems involved in this process.

Question:

Is there a way where by Enterprise Portal can automatically assign a "enterprise portal role"whenever a user ID in SAP SRM is created with a particular role. Your inputs will be of a great help. Thank you so much.

Thanks