http://dark-alex.org/index.php?Dark_Alex=m33
Get the 3.52 release, and it'll come with the installation notes, so its easy enough. When thats done, go for the 3.52-4 update, which again will have notes.
When you have that installed you get the 3.71 updater, and get 3.71-3 if you want.
When you've done that, enter Recovery Mode (turn on PSP while holding R) and find the option to turn off UMD detect or whatever its called, or ISOs wont run.
Now, I think you put ISOs in PSP=>Game=>ISO, but I'm not sure, I haven't used it in a while. PM me if you need anything else, I'll just hunt around a bit.
