This GTA liberty city stories trainer can run on any PSP firmwares! (no need for the cheat device save just this prx version and comes with addable cheats for the cheat device)
how to install:
1.) first of all, install this prx file for the trainer..ok here are the links 4 it:
For OE and 1.0 - 3.50:
http://www.megaupload.com/?d=SKBTP6WF

For 3.71 - 4.01
http://www.megaupload.com/?d=IJ8ZPH9O

For 5.00 - 5.50(All Gen)
http://www.megaupload.com/?d=9CKUDZWE

2.)now,put ur PSP in usb mode..then copy the prx file u just downloaded in the seplugins folder of your PSP...after that,copy this line at game.txt and vsh.txt: ms0:/seplugins/lcscheatdevice.prx Note for 3.71 - 4.01
ms0:/seplugins/lcscheatdevice371.prx

3.)now,go to recovery mode and go to plugins>>then enable lcscheatdevic.prx by pressing X

4.) launch the game and press L1 + up to open cheat device.. then..enjoy!! ;)

for more details refer to : http://www.youtube.com/watch?v=-R66WLdBd1k

Note: if u want to add more cheats for the cheat device,simply create a folder on ur PSP and just copy the cheats notepad on the Cheats folder..that's all! the cheat notepad already comes with cheats! plz comment for bugs!