It appears to be possible only from live CD. Therefore I’m not so sure that adding UEFI support to the live CD - as it was already suggested - would be a good idea. The missing UEFI boot turns out to be very helpful in such cases.
rEFIt - History of Apple and EFI
Which Intel Macs have 64-bit processors? Which have a 64-bit EFI?
On My iMac (mid 2007), installing from live CD and booting in BIOS emulation mode (with rEFIt) is AFAIK the only way to install today’s 64bit Linux. openSUSE 12.2 DVD doesn’t boot, gives you the choice between isolinux or ELILO but then nothing happens. Same with net install. And Ubuntu live CD - which has UEFI capabities - doesn’t boot either. Of course one can still install any 32bit Linux - I presume.