anytime i put an adjustable wastegate i first set it up without the boost controller.
run a vac line directly from the turbo to the wga and set the wga to hold 12-13 psi.that will give you your lowest setting when you put the bc in.after you have the wga set to your base you can put the bc in series from the turbo to the wga.
i.e:tee into the blue or green line and run a vac line to the in side of the boost controller,then out of the boost controller to the wastegate.
when you initially set the wga keep in mind that shortening the length of the rod will increase boost and lengthening will decrease boost.on a s2 wga i would begin by initially setting it so that you show about 2mm of threads on the arm.if that gives you 12-13 psi then youre good to go and can install the bc.
lets say you do that and you have 10 psi, loosen the locking nut and take the arm off the actual wastegate and turn it in one turn and hook it back up.keep doing that until you get th 12-13 psi
good luck
jay