now you mention it it looks like would be difficult to mount in wood CP. need to get mounting plate like one on groovy gear (works like happs trackball mounting plate).
True, you could probably make your own pretty easily tho. Get a metal hole punch the correct size and your set...
Looks like the pic is from ebay - would you get the whole lot? If so, just use the metal mounting plate already being used

(Edit: if it is big enough around the edges, hard to tell...)