SWITCH user from DIALOG to SERVICE, how???

hello:)

I'm developing the WD for ABAP app and have th following scenario to fulfill.

My service starts with the service user(no logon dialog) which was maintained with ICF.

Than with the

SUSR_INTERNET_USERSWITCH

I change to the DIALOG user. But how can I switch to another DIALOG user or back to the SERVICE user after that??

I know that I could close the browser, but I really would not like to do that.

any help is more than welcome

best regards

Simon:)