If you use regular security at AMS, so not the dedicated Sky Priority security entrance, you can use the 'Priority' lane with your StarAlliance Gold for Fast Track. If you use the main terminal security that goes upstairs, its on the left just as you leave the escalator, the main security continues to the right. Priority lanes are not reliably open I've noticed.

As a tip, the KL staff guarding the Sky Priority security entrance don't look very closely at your boarding cards so if you have an old one with big Sky Priority letters that usually works, the gates upstairs open for any valid (priority or not) boarding card.