cwiid-20110107-r1.ebuild contains this kernel option check: CONFIG_CHECK="BT_L2CAP INPUT_UINPUT" However, BT_L2CAP is gone in current kernel 3.6.0. Removing that check makes it compile again (though I haven't tested yet if it still works).
It looks like the BT_L2CAP option was removed even earlier than 3.6.0. It was in commit f1e91e1640d808d332498a6b09b2bcd01462eff9 (Dec. 2011) and is essentially always on (or at least on when bluetooth itself is enabled). Here is a link for convenience: http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=commit;h=f1e91e1640d808d332498a6b09b2bcd01462eff9.
looks to be solved in current ebuild