I think ASL scripts are the worst solution in your case. If you have several key positions, the best you can do is to create corresponding keyframes and Anim8or will find the positions in between.
I recommend using the traditional, simple key-framing method. You may find it uncomfortable to create many keyframes manually, but I think there's not a better way to do this...
The only (theoretical) way to automate the process would be to create a simple external program that reads a text file with the key positions and returns a piece of code you can paste into your an8 file... Anyway, something like this cannot be done using ASL and it's not worth writing such program unless you need to import thousands of keyframes.
As for ASL controller scripts, it's a perfect tool for simple, repetitive animations (for example infinite rotation, blinking light...), but this kind of animation would be pretty hard to implement.