Very Easily Actually
Steps:
Firstly re-update your PS3 to the original Sony 3.55 Firmware just to be safe and then...
1.Plug in USB, and format it to FAT32.
2.Create a folder inside the USB called PS3 then make another folder inside PS3 called UPDATE.
3.Put GEOHOT's CFW in the UPDATE folder on your USB.
4.Plug in your USB to the PS3, and go to System Update>Update via storage media.
Done