Bac's guides suck
The n64(NTSC one, at least) had 11 board types released and each one was slightly different. Some are easier to work with/trim down than others. You can use a 3rd party analog and use the same guide as using a gamecube analog on one of them.
RCP is the Reality Co-Processor of the n64, but most people refer RCP as RCP wiring, removing the cart slot area from the board and wiring the cartridge slot straight to the RCP/CPU/PIF chips on the n64's motherboard. (Makes the mobo smaller)