Here is a way to do a spline though waypoints:
http://dl.dropbox.com/u/5426011/example ... llrom.capx
A plugin could be made to hide the formula, but there isn't a way to make an in IDE node editor at this time.
Is it okay if I ask how you came up with the original spline? Is there a concept you followed to help you come up with the math inside of the 'Set position' action? I ask because I would really like direction in improving my own programming skills - of which I have none.
Edit: Lol, I didn't realize the actual name of the capx was the hint I needed.
Edit2: For anyone, like me, that couldn't get the array version working properly, you need to replace p.Count with Array.Width and (n-1) % Array.Width with n > 0 ? (n-1) % Array.Width : Array.Width-1, since when n = 0, you get -1, and I don't know how using -1 as an index affects arrays.