To hold track in place while the caulk, glue (or whatever you use) dries-and to get a good tight bond-lay various sized canned goods horizontally between the rails as weights.
You can also clamp the track. I use my wood templates for drawing curves and pieces of straight lumber sit on top of the track and then clamp it down while the glue dries (clamp goes udner subradbed and on top of templates and straight lumber. Can good, paint cans, weights and other things will work too.