Some people tap the manifold, some people "T" the brake booster, some people get a throttle body vacuum spacer I.E. BDL throttle body spacer, some people use a vacuum box like Golden Eagle makes. There are many ways to do it. Just pick one. If your mechanic has any concept of how bov's function, he should easily be able to figure it out.
Personally I picked up a BDL throttle body spacer because its baller. If I wouldn't have ran across a good deal I would have tapped the plate on the underside of the intake manifold that you can take off.
don't you have stock greddy turbo which has internal wastegate? tap the hose going from turbo to the acuator(did i spell it right? lol), but your best bet is to tap plate located bottom of intake manifold, or tap the big thick black hose located right on top of intake manifold.