OK well I have been trawling Google for the last half hour trying to find something for you but unfortunately there is nothing out there to unpack these files There were projects in the works for an .vpp_xbox2 Unpacker/Packer but is seems that the tools would unpack the files fine but they would repack them incorrectly I looked all over but it seems there is no tools available out there.
I've spent many a late nights looking for a 'misc_tables.vpp_xbox2' unpacker/packer, basically since the day I got my game and ripped the ISO for a backup. All I've been able to find is those useless "check here for Dual Wield" tools and PC version un/re packers. I'm not sure if anyone has tried just using the misc_tables.vpp_pc file from the PC version, unpacking it with a SR3 PC unpacker, modding it, repacking it, and replacing the Xbox's misc_tables.vpp_xbox2 with it (.VPP_PC). I've just been to lazy to do so as of yet. Send me a PM if you find that someone has FINALLY created one. (I will do the same) Good luck