I've done this. The reason you see nothing for Emulex drivers above AIX 433 is because that's when IBM started selling its version, the 6228 fiber channel adapter. This is just a rebadged 9002 Emulex. So of course, you need IBM drivers now for their piece of hardware. IBM would have you now buy feature code 6228 adapters (2Gb PCI) and under some apparent agreement with Emulex, Emulex no longer creates software for their adapter on AIX.
The good news is that you can still get that 9002 to work on AIX51. I've done this quite a few times. You need to install the IBM device driver software AND update the firmware on the fiber channel card to IBM's blessed version. The device driver is
devices.pci.df1000f9. Put the card in your host, install this driver, and then you can update the firmware on the card. Use the following website to get the firmware and follow the instructions:
http://techsupport.services.ibm.com/.../df1000f9.html
Once you do that and get it configed, it'll look just like a 6228 IBM HBA to the o/s.