Good info, thanks!
I've been able previously to tag my luggage through other airports (without a boarding pass), the check in staff would put a stand by sticker on my luggage, and I would just drop by the transfer counter and get the luggage registed for the onward flight.
This was with airlines from the same alliance.
Transfer without clearing immigration should be possible if I can get them to tag the luggage to the final destination?
HKG is a back up for the back up plan, but I have not been there since Kai Tak, so I'm a bit outdated to say the least.