I'm attempting to match a MIDI track to the tempo of an audio track without changing the audio's tempo. Problem is, the audio is an orchestral work and doesn't have good transients to lock onto -- the ones audiosnap finds are all over the map. I'm looking for strategies. One option I considered was to "drum" in rhythm with the track using a MIDI keyboard, mix the two together (with the drum prominent in the mix) onto a new track, and let audiosnap work on the result. I'm hoping there's an easier way -- any ideas?

Have you tried extreme EQ settings on the audio track? Sometimes tracks with a lot of audio information can be filtered to get a decent track for extracting extracting transients.