the basic concept of the crossfire enclosure opening is to make a 3/4" trouth for the runner to sit in. When I made my melamine enclosure, I did not create a trouth. I just used one piece of melamine to create the substrate barrier(bottom front piece), used melamine tape to edged the piece, and used liquid nails to glue the plastic track on top of the edge. I used small wood screws to hold the track down until the glue dried, then removed the screws so the glass would slide freely. The top slide was done the same way except I left the small wood screws in place because they didn't effect the glass slide.
so far, I have not had any issues with the 1/4" glass or the tracks.