I took my first microprocessing class last semester and used the M68DKIT912C32 development board for the 9S12C32 (48-pin LQFP). We programmed it in assembly. On the kit board a single switch controls whether the micro is in "load" or "run" mode. From taking measurements it looks like all this switch does is tie pin 48 (PP5/KWP5/PW5) to and from ground. I didn't see this mentioned in the datasheet, although the other required external circuitry is explained fairly well. Is this all that is needed for the 80-pin version to go between "load" and "run"? Any information would be greatly appreciated.
Pin PP5 has no special mode-control functionality for the microcontroller.
The M68DKIT912C32 relies on an special monitor program programmed into the MCU to give the PP5 pin this functionality. So if you want the same functionality on the 80-pin part you would need to program this monitor program onto the part. Read the TechArts manual for more information on the monitor program.
Whether you need to use this pin depends on your development environment. You have a choice of various approaches but the main two would probably be to use this monitor (with which you are already familiar) or use the S12 on-chip debugging support (called BDM). The BDM requires special hardware to connect to your PC - have a look for more information on this website including the TBDML module.