Mike, if you have a hammer drill, you may try what Rich & Ed suggested, before you spend the money on the core drill.

I would take a long 1/4-3/8" bit and drill through the wall so you'd have a reference point. Then I would make a few "honeycomb" holes around a couple of bricks. Then, take a hammer and chisel and start beating the crap out of it. Once I got a whole busted in the cinder block, I would repeat the process on the other side.

You can also use a masonary blade on a circular saw to cut around a few of the bricks. That would aid in their removal.

If you try it, the worse that can happen is you'll have a better start for the core drill. If it works, you've saved yourself some bucks.

Good luck and remember to wear saftey glasses!