WCF Receive Locations: WS-AT

Reading Biztalk 2006 R2 Do***entation about WS-AT, I found:

"Transactional submission is available only for one-way receive
locations. If a client attempts to submit messages in a transactional
scope for a two-way receive location, an exception will be returned
back to the client, and no messages will be suspended."

"The transactional scope is limited by the MessageBox. For example, a
BizTalk orchestration cannot participate in a client=92s transaction.
Similarly, a destination endpoint cannot participate in a transaction
that is initiated by a BizTalk orchestration."

I need to give a response to a client in a WS-AT transactional scope
initiated by the client application, but according to this
do***entation there is no way. Any Idea?

Thanks.