Mac step sequencer plug-in?

I don't know if this is kosher, but ... I would like to run a drum synthesizer as a plug-in within (ie. hosted by) AudioMulch. This synth takes a MIDI input. And I would like to trigger this synth with patterns I have written - as opposed to physically banging on keyboard, etc. So, I am looking for some kind of other plug-in that would enable me to create such patterns graphically and then use them to send the appropriate MIDI signals to the synth. Is this possible?

Or should I just do this externally, perhaps using a DAW's MIDI functions and mixing the synth sounds into AM's output (in recorded form, I suppose) in the DAW?

Thing is, I am enjoying AM so much - am using it real-time, my first music-making machine - and I don't really want to confuse things by incorporating another tool, but perhaps that is inevitable.