I need HELP on replacing factory 6x9's in 2003 cav

It seems that GM has made it very difficult for the average joe to change the factory 6x9's. I pulled my seats down and poped of the two side plastic molds there. I cant move that carboard/carpet thing above the speakers and when I tried I put a crack in my seatbelt holding plastic. Anyone who has done this or has a clue about where I can get some info please help! Thanks alot..