I have spent the last few days hacking the ps3 version, the methods and files seem identical to the xbox as tekken57 says. I have also solved the issue of random data corruption, what i have done is leave the original model files in place and just add the new files without replacing any of the old models.
For example if I was adding the new .pac for the rock I would leave ch100.pac in the pac folder and add 100.pac to the folder then change the plistPS3.h file to pac/ch/100.pac instead of the original pac/ch/ch100.pac.
So far this has solved all my issues with corrupt data. From what I can see the system must check the filesize of the ch100.pac and if it alters from the original it deletes the file. I hope this helps others who may have had trouble with it.