I created a simple excel tool for creating a gradient on sections of track where the 'apply gradient' doesn't quite work, such as curves and yards. This tool will tell you the grade, where to place the spline point and at what height to set it at for a gradual slope. All you have to do is measure the distance and obtain the start and end spline height. You can see and download the tool on my blog:
http://forums.auran.com/trainz/entry.php?1398-My-gradient-calculator
http://forums.auran.com/trainz/entry.php?1398-My-gradient-calculator