Al Dimeola seems to record his acoustic live stuff using all high end - starting with his Ovation, and heavy on the direct. I expect that the internal transducer is going to be critical; don't expect a run of the mill piezo to do it for you.
I'd track as many incoming signals simultaneously as I could - undersaddle, internal mic, small diaphragm condenser, SM57, LD condenser - each running to a discrete track if you can, and then start playing with the tracks.