This reminds me of my old sig
"Some people, when confronted with a problem, think 'I know, I'll use a threaded framework.' Now they have two problems."
Do it like this:
Create a TRequestStatus (TRS_A) as part of an active object
Create your thread (Thread B) passing in this thread's id (TID_A) and TRS_A
Do stuff until TRS_A changes from KRequestPending to something else
at this point the RunL of the AO will be called.
Set TRS_A to KRequestPending
Do something until you need to signal Thread A
Open a thread using id TID_A
Call RequestComplete using TRS_A - this will signal the ActiveScheduler in Thread A that a AO has been signaled and will start to process it.