Have you actually tried "dry fitting" that stem on your fork's steer tube? Maybe I'm not understanding you, but that stem will use normal steertube spacers. My wife has one on her bike, and it just uses regular spacers. The interface between the stem's steertube clamp and the steer tube is just like any other stem at the bottom - it sits on the spacers at a right angle. I also don't believe it requires a different compression plug for the steer tube. But it does require a special top cap if I'm not mistaken.