try using the software of the BT dongle...
the problem with the win soft of BT is that if BT dongle is not connected, then the COM port is not available also.
my soft keeps the COM port running all the time, and when ActiveSync starts, it checks on that port.
i go now with what i remember when using win driver.
supposing using win soft but having BT dongle connected when pc starts, then the com port is open.
add a com port under incomming connections. , make it COM9 or lower.
the connection on AS is under serial com port# (the same one you have set).
unpair the phone, and pair it again.
on the phone, try to sync over BT.
it should work.
this is what i remember when using win driver.
after that, ive changed to the driver of my dongle, and hopefully it keeps always the com port open, so i can plug the dongle at anytime, and it is running.
if that doesnt work let me know and i'll try to do what i did again to be sure how i didi it
good luck !