If you are not technically inclined yourself, get Speedworx to do it.
Cost of aftermarket manual tensioner: $50.00
Cost of rebuilding the engine as a result of buggering the cam timing and/or failing to set the tension correctly: $5000.00
I've found that the best way to adjust these is to put them in with the plunger retracted all the way then spin the bolt in with your fingers until you feel resistance slightly increase, then take the crankcase end cover off and rotate the engine with a ratchet slowly while continuing to apply tightening torque with your fingers to the tensioner's center bolt; once it finds an equilibrium position in which the bolt does not want to turn in any more with your fingers, back out approx 2 flats of the hex and lock it in place there.
DO NOT tighten the tensioning bolt with a wrench, use your fingers only!
Because this has to be done by feel ... do you have the right feel for it - or not??