Mark,
What is this “User Define Method” you speak of?
If you search the Menu space for the word “method”, you will see a command that allows you to create your own server and client side methods. These are reusable bits of code that you can call within your configurator. Unfortunately, they move with the Configurator and are not global at this time. Also, you cannot yet call an Epicor Function (which IS a global function in Epicor) from the Product Configurator.
So you could create a UD Client Side method that clears out a group of related fields and call it from several places within your configurator. They show up in the Expression Builder too.
Mark W.