I dare say the requirements are nothing more than artistic talent, and the word "Project 64" being in the logo.
Preferably all self made material, and nothing thats copyrighted by another company, so yes bang goes the hot idea of having Mario64 characters randomly placed over it
When I did the PCSX2 logo, I went for something very simple, yet at the same time, something that could be identified with the PS2, all the logo work, site menus, and 'special' video releases have 'iconic' elements from the PS2 BIOS screen and menus.
(see attachment)
Look for something that embodies what the N64 is, the N 3D logo could be done...but as a spin-off using 'PJ', the N64 is also known for it's strong cartoonish graphics and zelda RPGS, perhaps borrow those styles and incorporate them into your logo.