BBS, Jongblood and several others make center lock wheels. These are intended for racing and usually require a change of hub, spindle, possibly rotor/caliper and caliper mount. You can be looking at as much as $5000 per corner. There's a reason only big time race teams use them (and why this small time racer doesn't) There are no adapters that I am aware of. If none of this scares you off you can check out
http://www.hrpworld.com.html they have everything you'll need. Ask for Brian and tell 'em I sent ya'-Keith /:\