Discount on monthly memberships

I have a quick question about setting up a coupon in your membership pluign.

We would like to offer a 10% discount on our basic subscription plan, but have that 10% coupon apply every month when the member is charged their renewal. Is there a way to setup a coupon to do this? If not is there a simple way that we could manually set someones subscription to auto renew every month at the discounted rate?

thanks
Samuel