Mr. Microchip has some samples for USB development using MPLAB + C18 compiler (free for limited optimizations). I have compiled and used this samples (from Microchip) without problems, and VID & PID can be changed in source without problems. At PC side I have a sample code in C++ Builder, that can be used as a base for your develpoment purposes. At PC side, you can change the PID and VID too. WinPIC and JDM are just flash tools, and can't change the code. I think that code doesn't work well or this tools doesn't support this device, but VID and PID can't be omitted for this tools.