you can get p90 pickups that are basically humbuckers in the p90 housing. EMG pickups are kinda sterile and for metal so you probably don't want them but here's a link to their site were there's an example of the kind of stuff you can get. These are active pickups so i don't think you'll want them but at least you know they exist...

http://www.emginc.com/displayproducts.asp?section=Guitar&categoryid=10