User scheduling

I read the to do list and did not see this listed. I would like to have a user be able to create there own evevt (or edit an event) on signup. This would be for scheduling a private appointment or lesson. A user can sign up and pay, then be redirected to add (or edit) the time/date of the appointment against availability in the calendar. Prefer using cck cal/date. If this is aleady possible can you please explain briefly the implementation or what other modules may make it work.

Thank you for the great module.