Yes, that is possible. You can hook up your V drum pad to MPC via MIDI and trigger samples from MPC by playing on the drum pad. You'll need to make a program and assign note numbers to MPC pads that would correspond to MIDI note numbers, transmitted by the V drum pad (you can check V drum's manual for that, or easily find it out by connecting drum pad to a DAW via MIDI interface and playing on it: the incoming MIDI note events and their numbers are usually visible somewhere in the DAW's transport panel).
You can also try to find out, if there are any factory samples in the Internal flash of MPC. Press Mode + pad 2 (Load Mode). Scroll to Load: Autoload. If it is set to "off", set it to "on". Then switch off your MPC, wait for a few moments, then switch it on again. If there are any samples in the Internal flash, they will load to RAM (if you have already bought a CF card and inserted it into MPC, eject it before switching MPC on).
Here is an archive with MPC 500 factory sound bank (as it was in the CF card that came in the box):
http://www.sendspace.com/file/wj7se7 (68 Mb). You can use a 128 Mb Compact Flash card as a host for this library.