Ok, when i bought my XT here on Talkbass, the original owner (TBér coronado3, who did a great job!) fashioned his own pivot plate using materials that anyone should be able to find at their local hardware store.
Here are pics of the front and back fully assembled.
Here is a pic of the back with the pivot plate removed. There is a threaded insert in there.
Here is a picture of all the parts (which isn't much!). Two chicago style screws with washers. Actual screws are about 3/16"long. 1/4"x 1 1/4" screw with a rounded head and a metal washer which attaches the pivot plate to the actual body via the threaded insert. I bought a thick rubber washer to sit between the pivot plate and the XT body. The actual pivot plate crafted from some smoked 1/4" thick plexi glass.
Here is a pic of the actual pivot plate held up to the light (yeah, the cracks look bad, but you don't see them when everything is together....

).
I use some blue loctite to keep everything snug. The only gripe, is the rubber washer as it will squeak if i adjust the position. I am searching for a different option, or i may try some silicone spray. EDIT: Replaced the rubber washer with a nylon one, and all is good...

no squeaks and it moves freely when i want it to.
Anyways, i think I have everything listed out there. The dimensions of my pivot plate are a bit larger than the ones found here
http://www.talkbass.com/forum/f8/steinberger-club-476471/index20.html#post14713148 (big thanks to HomesickBob for posting these!)but if you use these measurements, and the hardware i listed, i am sure you'll be fine.
Post here, or PM me if you have any questions. I'll do my best to respond.
Good Luck!