It would need a short script written, you could do it yourself if you're comfortable with some javascript, or someone from the community might already have something almost-suitable that needs a bit of tweaking over in the API forum (not mentioning Aaron's name). As you've described it, it's pretty straight-forward so more than likely someone can have a solution for you pretty quickly. One minor detail, the API doesn't react to Attribute changes like a sheetworker - it would more likely trigger from a chat command from the GM which increases the Attribute, then changes the side of the token.