I just went through this myself, here's what you gotta do. First install another launcher from the market such as the gingerbread launcher. Next you must uninstall launcher.apk from the system/app folder using a file manager program. Reboot. Now return to the market and you will be able to install the new adw launcher.
unless p3 released new kernels his previous kernels do not support compcache. and adw Fc's are bc adw is built into the rom and to update it, it needs to be in /system/app to replace the current launcher.