Ok, I tried to stay out of this one, but.................
There are EFI FirmWare Updates listed on Apple's site.
And Even A Boot CD to RECOVER FROM A BAD FLASH.
So, if you really want to try this go to
Firmware Restoration CD
GET THE CORRECT CD FOR YOUR MAC. BURN IT.
MAKE SURE IT WORKS
MAKE SURE IT WORKS
Then find the
EFI FIRMWARE UPDATE for your Mac and the 64bit EFI Update that you think is close to your Hardware.
Figure out what the update app that runs in OS X and the one that Does the Flashing in EFI are LOOKING for The FirmWare and HardWare to Match.
Once you Have Hacked the Updater for you Machine to take the NEW 64bit Update, FLASH IT.
GET OUT YOUR RECOVERY CD.
1. REBOOT TO YOUR USELESS MAC.(99% Chance)
2. REBOOT TO YOUR 64BiT MAC(1% Chance)
I won't go into how to Edit/Hack the Firmware update to Flash your Mac with a 64Bit firmware, because if you can't figure that part out yourself, it's not something YOU need to be Doing, but it CAN BE DONE.
I will give a Hint:
Hexedit
DISCLAIMER:
ALL OF THE ABOVE IS NOT ENDORSED OR RECOMMENDED BY ME, OR ANYONE, IF YOU SHOULD FIGURE IT OUT, AND BE BRAVE, STUPID, CRAZY ENOUGH TO TRY IT.
YOU ARE THE ONLY ONE TO BLAME IF IT BURNS YOU HOUSE DOWN, KNOCKS UP YOUR DOG, KILLS YOUR MAC, ETC>ETC>ECT.