I've updated the SystemGenerator wiki page to include new versions of the 8 and 16-bit device file generators. Sysgen08 and Sysgen16 V1.2 no longer require MPLAB files, and will work with MPLABX installations. They work similar to the previous versions... just point the program to the proper MPASM/MPASMX folder (8-bit) or the XC16 folder (16-bit).
The 16-bit version also allows you to generate files for the PIC30/dsPIC33 families (over 494 devices!).
There were quite a number of changes involved, so if you run across any issues let me know.