Portal Logon page in WebDynpro ABAP

Dear Experts,

We have an WD ABAP application that is called anonymously.

A user is configured in the SICF Service.

Once the user enters his logon data in the WebDynpro, we call the function module

SUSR_INTERNET_USERSWITCH and change the current user at runtime.

Now we want to use this WebDynpro as a Portal Logon page.

We want to use an anonymous logon in the Portal.

After the User has logged on to the ABAP Stack, we need to update the Portal session and change the user there also.

Is this possible?

If yes, how can we change the user of the Portal session from the ABAP stack?

We are using the ABAP stack for user Management.

Any help appreciated.

Regards,

Jürgen