Install Airport/Bluetooth on a late 2005 G5 Powermac - possible?

I have now discovered that my "acquired" G5 Powermac is the Late-2005
2.3 GHz model and was delivered without the Airport/Bluetooth card
installed :-(

All the "official" forums I have found say that this can only be
installed by Apple and to go to the Genius. Is that true ? There are
a number of the cards (AirPort Extreme with Bluetooth 2.0+EDR)
available on eBay that I might go for if it is an easy fit.

I guess I could also go the PCI card route for Wireless and a
Bluetooth module - but it's not so elegant.

Thanks for any help