If you do it right, you can have the dust washer right under the top of the CP where it belongs.
It'll require a router with a straight bit, and some plexiglass.
Cut a piece of plexi about the same size as the joystick.
Mark where you want your joystick to go. Including center and mouting holes.
Place the plexi on top of the wood and trace with a pen or pencil.
Adjust your router to the thickness of the plexi. I recommend 1/8" plexi. Route out that area, keeping about 1/8" away from the border you traced.
Get a hammer and chisel. Go around the traces and remove the rest. This will insure a perfect fit of the plexi.
If you have a compass you can trace a circle where the dust washer will go. Get a piece of boxboard (like a cereal box). Stack the plexi, the boxboard and the dust washer. Adjust the router to the that height.
Route out the circle you just traced.
Line up your joystick bottom. See where the holes for the bolts are? Mark them, then route an area for T nuts. Well, you can either route or use a spade/forstner bit. You just want to go down a little bit, about 1/8". Then drill out the holes for the bolts.
Tap in your T nuts in the recesses you just made.
Place your plexi in the recess. Drill your 1 1/8" hole thru, *from the bottom*. Remove the plexi. It should now have a hole in it.
Gluing the plexi in is optional, but you can if you wish. Lay the dust washer in the recess, and cover with the plexi. Then install the joystick bottom. Bolts go thru, up into the CP, completely invisible to the outside.
When you have your overlay on top it will hold the plexi in place. Polyurethane glue will hold it if you want, but use it *sparingly* as it expands a *lot*. You don't want it bleeding into the area the dust washer is. If it does you can move the washer around a bit to break it up, then tap it out the hole. And of course remember to clamp it down firmly.
I hope I covered everything. I've done it now with several CPs, and next time I'll be sure and make a photo tutorial. Any questions, feel free to ask.