Manual nothing. Just open the Track Menu Tab and play with the tools.... They're not overly Hard to figure out. Bill had it right. Set the Height you want at the Spline Point with the Height Tool (Either manually select it, or just by playing with it by hand), and then use the "Set Terrain to Spline" Tool to bring the ground up. You might actually want to set the height of every spline point and make them yellow. This gives you the option to play with the Terrain around it without screwing up the Track in the process.
Word of caution though, when adjusting terrain height under the track, I've found alot of Track is set too high off the ground for my tastes, so you get this odd floaty effect (Usually I think this is an attempt at making uneven Ballast Lines, but I don't really care for it), and the way to offset that is to then raise the ground later either by hand or use a second piece of track over the first at the height you want (Usually .15 more is about ideal for this). If the track is 0% grade you can just use the Terrain "Set Height to" Tool, but this is impossible for track on a grade generally.
Falcus