[jakep]

No, you do not have to change any of the sourcecode to use a different programmer.

The comments are unfortunately somewhat misleading, which pins you use for programming are built into the chip itself. The reason for that comment was that we had to move around some of our inputs to make sure the MCLR pin was free to be wired to a custom programmer. This way, we can wire an unused pin on the PS2 plug to MCLR, and when we want to program the chip, we can apply 12volts to that pin and not worry about any of the voltage flowing to the sensitive digipots.