Yeah, perhaps photos would be appropriate. In the meantime, how about a better description?
I have the sidemounts bolted to the seat and to the top of the sliders. The sliders are bolted to the sidemounts and your seat rail. All that seems fine. The problem comes when screwing the rail to the stock mounting points on the tub. I don't think I have the screws in backwards, because they can only go in one way: from the top. The screw heads are both tall and wide enough that, when I try to slide the sliders forward of the middle, the top (sliding) part of the slider hits the screw heads on the front two screws holding the rail to the tub. Like I said, going to socket-head cap screws doesn't give enough clearance. I've been looking for some low-head socket cap screws or truss-head screws, but those are difficult to find in 10x1.25, and I figure that I must be doing something wrong, because you said that most people use this rail with Sparco sliders.
Any guidance you can give me would be greatly appreciated.
2009, STR & DD. 1995, HPDE. 2004 MSM, sold. 2010 Mazda3, hers.