There's a link to some interesting 8048 projects from the wikipedia entry, including disassembly from ROMs. Mind you, he's working from game ROMs posted to the net, so they're already in software form. Getting them out of the chip ..... :?:

A better bet might be finding another micro with USB and/or serial (/edit/ Bluetooth?), that'll drop in or adapt to the pinout, and writing your own code. There are current 8051 versions to suit; PIC and AVR too.