Due to their being a update for the game that only requires 3.50, this game is playable on CFW. No 3.60/3.65 keys were hacked/found to make this playable
To boot Duke Nukem Forever on CFW 3.55:
1. Insert Disc in PS3
2. Start Multiman
3. Highlight Duke Nukem and press Triangle.
4. Select UPDATE
5. Save the file [28MBish]
6. Exit to XMB
7. Install update via PACKAGE INSTALLER
8. Boot Game via MM allowing MM to change PARAM.SFO
Direct link to update found: HERE
For more information, visit damox's thread right here: PSX-SCENE
Thanks to damox for the information!