I came across not to long ago, and thought I would share it with anyone who was interested in starting emulatin. It covers basic arcade emu... Though its not 'PSP specific' its still a pretty useful doc!
Sorry, I can't provide a better link on a server, but QJ won't host this file because it's too big :P
edit more reliable link: http://www.psp-stuff.com/arcade_emu.txt