My english is not the best but I try my best to explain you...
- a OFW PS3
- a CFW PS3
- The console id and Mac Adress from your OFW PS3
Before we begin.. you do this to your own risk!!!!
I've done this with CECH-G PS3's so I don't know how it looks on different models!!!
Change the Mac-Adress from your CFW System PERMAMENTLY, we take the Mac-Adress from your OFW System. Now we change the console id from your CFW System PERMAMENTLY, we take the console id from your OFW System. (Better you Backup everything, later you can then restore...)
Now just restart your CFW System then start multiMAN and look to your IDPS. If it shows the console id from your OFW PS3 then you're on the right way. Now you muss update your CFW PS3. If your OFW PS3 on 4.30 then you muss update to 4.30 CFW but if your OFW PS3 on 4.31 then you muss update to 4.31 CFW. If you done with the update, now we take the HDD from your OFW PS3 and attach it to your CFW System. Now turn on your PS3. If it don't want to format the HDD then you're on the right way. Now you can use one HDD on both PS3 1x on CFW and 1x on OFW. It will don't format because your CFW PS3 are like a clone from your OFW PS3 (remember, we changed the console id and Mac Adress). Now we copy the 999 DWG CFW by Rebug to a FAT32 formatted USB (PS3>UPDATE>PS3UPDAT.PUP) and attach the USB Drive to your CFW PS3. Now we just Copy the 999 DWG FW over the XMB. Wait up to 100% and then the other screen comes with the Firmware Installation BUT WE NOT INSTALL THIS just deattach the power cable on your CFW PS3. Now we take the HDD from your CFW PS3 and attach it to the OFW PS3. If we now turn on our OFW System it will directly begin with the Installation screen. The FW (999 DWG) will now just Install on your OFW System without any errorcode's or corrupted data because the FW is already checked on your clone CFW PS3 on the OFW it will only searching and then simply it will install.
You're done! Enjoy your CFW... Don't ask for any links or how to change the Mac Adress/console id. Google is your friend.