How to require certain format for employee ID on forms

We recently started requiring employee ID's on forms that we get sent for signature, which are in the format XX-###### (ex: FW-003781 or AH-940201). But even with a note that pops up over the text box saying to include the hyphen and all characters when filling it in, people STILL fill it out wrong. They either put only the numbers, or leave out the hypen, or if there are zeros in the first digits they leave them out. But since it contains letters, numbers and a symbol, I can't use the preset requirements.

Is is possible to use the custom fill option to make them have to enter into the box 2 letters, hypen, 6 numbers and no other format be acceptable? If yes, what would the code or script entered in have to be in order to format it like the example ID number?