Is it possible to enable the FirePro 30-bit color support on Linux?

I tried setting Depth 30 in xorg.conf and got the not-unexpected error:
(EE) fglrx(0): Given depth (30) is not supported by fglrx driver
I am using the 8.72.11 driver on Ubuntu 10.04.

And before anyone asks, I do have a 30 bit LCD.