I am happy with my cingular treo 650 overall, but am royally pissed at palm in that sprint units have been able to pair with my carkit since, June - still can't with cingular. What is even more insulting is that in the last few weeks, they changed the website to indicate that it is compatible with my carkit (BMW), yet made no changes in the software to accomplish this. A blatant lie - a cursory review of any treo forum confirms this.

I would like to put the bluetooth stuff from sprint into my cingular, otherwise leave it alone.

Has anyone tried making a custom ROM to do this? Will it work? Which files should I replace?

Palm claims that it is so difficult because GSM radios are so much more complicated than CDMA. This doesn't ring true to me.