I don't know if the Tribute pickup mounting is the same as the basses, but if it looks like the pickups have 2 phillips head screws and 2 mysterious holes, then it is like the basses.
The pickup adjustment is really clever. Under the mysterious holes are two more phillips head screws similar to the ones that you can see. To adjust the pickup height and angle, you loosen the two screws that you can see. Then, you adjust the height of the two screws that you can't see (you will probably need a smaller screwdriver with a narrow shaft, but don't worry, all the screws go into threaded inserts and should turn pretty easily). You can move these hidden screws up and down until you like the height and angle. Then tighten the top side screws down to lock the pickup position into place.
What a great solution! Somebody has to tell you the secret of how it works, but there's no special hardware or tools required. No springs or little pieces of rubber tubing either. You can finely adjust the position of the pickup, then lock it down solidly. Just awesome.
I tried looking at some of the guitar pictures and it wasn't clear that this mechanism was used. Seemed like the single coil pickup only had two screws.
Hope this helps. Post the answer when you find it. I'm curious how the guitars are done if they're not like the basses.
David Fung