TOPIC: Seats remaining in event on a custom events details page

Does anyone have any ideas about how I can get the number of open seats to be available on a custom events details page?

I don't use the events listing in DTRegister to show my events. I use a customized calendar (the built-in one does not meet my needs).

I'd like to eliminate the phone calls from customers who want to know if there are X number of seats left in an event.

Best case: shows automatically, similar to how this happens when the built-in events listing is used

Next-best case: a link the user can click on to display the information.

My calendar of events: http://www.whimsyartstudio.com/current-month

A sample events details page: http://www.whimsyartstudio.com/calendar/032914-5

Any ideas would be helpful.