Ok first off you need to get this. http://dl.qj.net/Quake-v2.0-PSP-Home.../893/catid/195 REMEMBER****** Rename the folder quake-psp. and dont download the shareware, just keep the Eboot file, its important.
Next you have to download this file
In the quake-psp file, put the ID1 or whatever its called file in there, and nothing else. There you are good to go, hope this helps.