Fireplaces, Heating Stoves, Flues and Chimneys - Feesable to add vents to my old brick fireplace?

I am wondering if adding fresh air vents to my old (1919) brick fireplace is a good and smart idea. My whole idea is to add some fairly tight glass doors to it and get some fresh air "injected" into the fire. I think this would let me burn more effecently and not lose all my heat up the chimney. My buddy has a newer insert fireplace and it has vents plumbed right to the outside. Great design in my opinion.
One idea is that my ash dump could be used as a vent, bringing cold air up from the basement to feed the fire. Could that work?
Or, considering my fireplace is on an exterior wall, could I add a vent directly thru the back to the outside? Maybe put like two 2" pipes thru the brick (and siding since the chimney isn't visible from the outside until the roof).

Any ideas on adding vents to a regular old brick fireplace???