Formit + Constant Contact

Is there a good method of doing this? I found Bob's ConstantContact plugin, but not really sure how to use it.

The Situation
I have a contact form with a checkbox to subscribe to a newsletter. I created the list in ConstantContact. The Form is using FormIt to submit the data (and save to DB). I would like it so that if the user selects the checkbox, then it submits the form normally, but then adds the contact to the new list in CC.

The other form is just a simple email field that I should just be able to link up to CC, no?