well all u hav to do is a simple umd swap i usedthe gta lcs umd and it works with the original demo umd also (u can use any umd)
all u do is put the umd go to game press x and wen psp comes up quickly put vice city stories in and it should work
i made the stupid mistake of updating to 2.80 and i am not updating it cause ther mite be a devhookor downgrader for it
i also hav a vid of this working

cheers luke :)