You will Need :
1.custom firmware or 1.50/1.0 or homebrew enablers such a dev hook
2. For downgrading info and custom firmware installation check my other posts
3.extract your homebrew app
- lets take mapthis! for instance
- on opening the mapthis! folder there is a 1.50 and 3.xx folder
- depending upon your firmware copy one of these to memory stick>psp>game?game150 or game3xx
- disconnect your psp and go to game>memory stick on your psp
- your psp homebrew game /application should be there!!!
- If there isnt a 1.50 /3.xx folder within your homebrew zip/rar file
copy the entire folder to game150/game3xx
Should work in most cases