ps2 is easily moddable just need a copy of agent under fire or an action replay max :p
and its easy from there :D
the wii and 360 easy, just need the firmware via usb key or a certain software or install a modchip( the latter I recommend getting it down for you)
Former you can do yourself
Ps3 you just need a dangle but its too much effort, not many games are playable on it.
also the only the I have actually modded is my psp, not bothering with anything else but I know how.