Booking System for Agriya's GroupDeal script

I want to customize my groupdeal script putting into it a "booking system" avaiable for each deal The admin backend for creating the deal will have this option of enabling the booking or not The idea is when the user go to the purchase page, selects a timeslot then pays and if the purchase is confirmed this timeslot is filled This system needs to be very flexible, as I can create different periods - timeslots, how many persons per timeslot, etc- within the same day