i don't know for sure if that phone has a sim card, but generally speaking you have to get the carrier (verizon) to unlock the sim slot on any "global" phone before a sim from another carrier can be used on it. There is also the issue of having access to the correct radio frequencies for the Hong Kong carrier... My guess is that you would be better off buying when you get there.
..somewhat related (FYI), TBH just released a CWR flashable zip to unlock additional frequencies on the droid pro and droid 2 global...
TBH US GSM Band Unlock for Droid 2 Global and Pro Update.zip Public Release
