How are recording steps encoded? Can they be decoded?

I have a huge transaction recording in which I need to change one click in a step right at the beginning of the transaction. I really don't want to re-create the whole recording from there, because it's a long transaction with lots of extra checking for text and images. All I need to do is change the name of a text field that gets selected at the beginning of the transaction (it's a trivial change, on the order of changing a field name from "Username" to "user_name").

Is there a way to decode the saved step, edit the content, encode the revised step, and save the revised step.