Some say no, but I tried last time I had a custom ROM on and it bricked it lol. So I will stock everything and then update to it and then slowly add my stuff again. There might be a easier way but I only suggest and do what I know of course.
You guys are sorely misinformed. The current 2.2 ROMs are built off the 2.2.1 update released for testing in Europe, and IS in fact 2.2 (this is the reason you have to Flash the 2.2 SBF file and re-root before installing a ROM, and apply radio file updates, as the rest of us don't use European radio files). The previous ROMs such as CM6 (October 10/16/2010 and earlier) and Dexters MotoFrenzy were 2.2 overlays over 2.1, but now have been upgraded to ACTUAL 2.2, along with G.O.T.
TelusMilestone, PLEASE stop spreading this misinformation in every single 2.2 ROM related thread. You consistently show your lack of knowledge concerning them.