Man, this reminds me of the "how can I develope my lower bicep" post. I know people will dissagree with me (and they have every right to) but I feel that the muscle is the muscle, and while you can effect the over all shape and size of it, you can't specifically work one part. A muscle contracts as a whole.
The main thing most people need to do to get a great inner chest/bicep peak, or whatever, is just increase the over all size of the muscle. If that sounds too simple, thats becsue it is, but since it isn't a magic bullet people don't want to hear it.
I just know someone is going to come back quoting Arnold in his damned Bodybuilding Encyclopedia to contradict me (and they have the right to I guess). God I hate that book.