Custom Login module for a specific customer requirement

Hi,

I have a customer requirement where they want to allow customer to login to portal with either email id or user id. We are connected to ABAP data source for UME.

and the NW Portal version 7.01 SP15.

I have set the LoginwithAlias property to FALSE in visual admin. So that the user id will be picked for login authentication.

Can some one suggest me a working solution for enabling login via email id as well ?

Thanks,

Manchari. N