Hey ok first off I will start by saying yes this does not work for some games like GT5 for example but it will work for the majority of games.
NOTE: This is for games larger than 10GB but if the same thing happens with games that are less then try this too.
I have MultiMan 1.15.03 so if your not running it and have problems I can't help you.
Here we go:
First Step: Insert game you want to copy and boot up MultiMan, select backup with O.
Select whatever one you want, if you have a storage media device attached then select cancel on backup to internal and your storage device will come up as next option.
2nd Step: Once its all done copying, remove your storage device and connect it to your computer.
3rd Step: Go into the folder with your freshly copied game and in the folder name it will have an underscore at the start, REMOVE ONLY THE UNDERSCORE.
*If the Game Name comes up after the BCES00... then delete that too, GT5 did this but gets to loading and stops.
4th Step: Remove storage device from PC and reconnect it with your ps3.
5th Step: Boot up MultiMan (with a different game in the drive to be sure that it worked) and load up the game, remember to press no for booting straight away.
6th Step: Select the game on home, should have replaced game in the drive and you are done.
NOTE: This worked for Resistance FOM completely and Gran Turismo 5 got up to the loading screen (still working on it)
If this helped you please post a reply for confirmation.