How to set bpp 16 as default?

["Wathen, Metherion" <mwathen@bsadesign.com>]

Hi all,
How do I set up X to default to 16 bit color depth?

Im running Debian Potato 2.2 and am running the version of XFree that
shipped with it. (sorry dont remember xf86 version #). I've tried to add the
line "DefaultColorDepth 16" to my XConfig file but the server just croaks on
it. In fact I didn't see anything that indicated what the default color
depth was. :{
My video is on-board Cirrus Logic 543x with 1Mb ram (yeah I know not a lot
but should be able to do 16bit @ 800x600, at least)

Thanks in advance,
mw.