Also, I forgot his name but he's always being recommended on the seymour duncan forum...anyway, the guy who runs this site makes pickup rings for the active bass-housing EMG pickups (707, 81-7 etc)
http://www.fretsonthenet.net/other_parts.htm they're near the bottom.
They don't actually hold the pickup up like 6-string ones do, but they make them look normal and cover up poor routing jobs :p