Small customizing to a wordpress fourm

I'm using gravity forum. Basically its a forum a front end user can you fill out and it creates a post on the site. I need someone to customize a tag field within the forum(enter the providers phone number is this format 7775551212) - [login to view URL] attached below but the phone number outputs like this 777-555-1212 You would need to write a customization that gets the value of the field and transforms it into that format above. This can be accomplished using available hooks. Your custom PHP would go in my themes [login to view URL] file. I need this done in a few hours.