Ive programmed an arduino to replace the CNT-NUS chip.
It suports rumble.
You can use to use the N64 original or PS2/Gamecube style joysticks.
And it emulates a memory card with an eeprom. (untested, waiting on eeprom in mail)
I have tested this with rumble on an atmega328, atmega328P, and atmega168. All work great!
heres my code:
A stand alone replacement to the Nintendo CNT-NUS N64 controller chip, with built in rumble, for use in portables. - jtryba/atmega328-N64-controller
github.com
Ill work on getting diagrams posted as well.