This will only work with the main game not the 2 dlc's.
Basically, your gonna rebuild the non complete edition of GTA IV.
you can find the Icon0.png in the installed game data.
Use PS3SFOEDIT to change the game name and id
Download the EBOOT for BLUS30127.
I recommend the US EBOOT because I heard the Euro version is censored.
1. Create a folder called BLUS30127 in your GAMES directory.
2. Inside of the above folder create a folder called PS3_GAME
3. Inside of the above folder write a copy of the Icon0.png and edited PARAM.SFO . Now in this same folder create a folder called USRDIR
4. Navigate to your backup of the complete edition and enter it's USRDIR folder, and go into the folder called IV, move or copy everything in this folder except for update to the USRDIR you created in step 3.