Can You Trigger Midi Event - Drums Live MainStage

Hi Everyone.

Is it possible to trigger a sound in Ultrabeat or EXS24 from an audio signal? I just want to be able to trigger alternate drum sounds when using the kick and snare drums. I understand that the world of audio to midi conversion is a big one but I just wondered is there a way for MainStage to recognise it has an audio signal transient and trigger an already set midi note event. In Logic you can replace drum tracks with ease. A noise gate is able to detect when the signal is there and a side chain is able to get things to react with each other..... Any ideas??

Thanks

Damian