membership intro price then auto subscribe (is this possible?)

Hello, I have been looking through the forums and most of the posts are about the menu not showing up etc. I have the membership working find at http://proforceathletics.net

I integrated it into the slide down panel so all membership content is accessible through menus in there.
(pretty cool you should check it out!)
It shows one set of menus for non-members and another if you are logged in (a member)

Now the client wants is to allow access to the membership through an intro price (free) via coupon offered at a social site for a limited time. He wants them to have to sign up thereby giving their CC info to sign up for the free trial but if they don't opt out by 30 days then it begins charging them the monthly rate.

My thought was this: if they signed up with a coupon but how do I get this done? Can I just have them sign up for the monthly subscription amount and give them a coupon for the amount of 1 month? If so how can I offer this with the available options?