Edit: Oh, I think I get what you're saying. Like, if you have three different modes for a script, and you want to ask the user for different parameters in each mode? No, I doubt it. In situations like that, I've just registered all the params for every choice and ignored the ones that don't apply to the selected choice. It's not pretty, but it works.

Here's a tip, though: I like to store my script settings in static fields. In Java, static fields are associated with the class instead of the object, so they retain their value between script invocations. Copy the static values into Parameters in your initScript, and then copy the values back out of the Parameters and into the static fields in your runScript.