Set user login before call WD application

Hello!

We calling WD application from SAP CRM B2B. Both applications requires authentification. Both applications works with users maintained thru SU01. But CRM can use user aliases and WD application can use ony logins which not so comfortable for users since logins has values too difficult to remember.

So we want to setup WD application in this way:

1) pass current user's login as special URL parameter

2) during load logon screen WD application read this parameter and automatically put this value into "user login" field and disable it

3) so user should only enter a password

So does WD application have such special URL parameter and is it possible to setup that value of this parameter will automatically put to "user login" field when application will be called?

Regards, Lev