Hi,
Newbie here.
What I do (mind you, I'm not set up for MIDI) is assign the kick to Main output, panned hard left. I assign the snare to Main output panned right. I then assign toms, h/hat, etc. to Aux output (which is stereo) and pan them across that wherever I want them. Stereo Aux output is split into two separate cables.
That way I record my drums across four separate tracks on my Zoom R24.
If you want to get real clever, once again without MIDI, (and yes, I know MIDI would be much better!) you can do what I used to do with my old SR16......
Split any given kit into two separate kits, so that say, Kit 1 has kick, snare, hi-hat and ride assigned to the (effectively) four outputs of the SR18. The rest of that kit is muted right down.
Kit 2 has say two crashes and the toms assigned to it's four outputs. The rest of that kit is muted right down.
You record the song using Kit 1 into four tracks of your recorder.
You then switch over to Kit 2, plugging the leads into the next four inputs of your recorder, and, with practice/coordination, you can record another four tracks of drums.
So you now have 8 separate tracks of drums to mix as you like.
At first it's kinda tricky to synch the second Kit with the first, but it gets easier with practice, and if you mix later in your computer it's dead easy, because you just drag those tracks into synch with the rest.
Very much a low-brow method, but it does work.
I've only just bought my SR18, so I haven't tried the second method yet. It worked with the old SR16, so it should also work with this newer machine.