Have you actually read this thread http://www.ps3news.com/forums/ps3-ha...ve-115836.html ?
There is a lot of info that helps!!
Alternatively you can try this:
1. Jailbreak ps3 like normal with downgrade payload - power cycle
2. PS3 should blink a bit and shutdown again
3. Remove iPod from PS3
4. Turn on PS3 and confirm you are in factory mode (big red box)
5. Download DGF.rar, you will find the link in the thread above
6. Put the file 1 self file on an empty usb-stick, aswell as the modified 3.41 pup
7. Plug in the most right usb slot and start ps3 (normal, not jailbroken)
8. After about 3 minutes it should power off
9. Remove usb and boot normally to see if downgrade was succesfull
10. Put the file 2 self file on the usb stick (remove the file 1 and the pup)
11. Plug in usb stick and boot ps3
12. Remove usb and start ps3
NOTE: YOU MIGHT LOSE YOUR BD PLAYBACK ABILITY IF YOU DOWNGRADE SO USE THIS SOLELY AT YOUR OWN RISK!
Hope this helps