what do you mean by multiple parts? like, .r01, .r02, .r03, etc. files? if so, then just use winrar to extract them and you'll get your game.
that's what i said, extract them all and you should get the iso. to extract, use winrar. https://www.romulation.org/forum/index.php?topic=1663.0
i know how to extract a rar file. But I'm just wondering how its going to work, having a game in three parts on my psp...
the game wont be in three parts on your psp it will be combined into one .iso when you ectract it from the .rar.
Put all parts into the same place, and extract the first file. All 3 parts shall merge-pure and simple. Some may require a joining program-if your using www.pspisoz.com like I am-it's not needed for those.