I've never used a juno, but assuming it's a real synth, you can't get more than one channel out of it. a Triton/motiff style "synth" (as they call em) are PCM based. In other words, your editing pre-created samples, so the processor can do 16 different sounds at a time with no problem. With a synth, you can make sounds from almost scratch. The digital ones may use samples also, but you can contort and bend them into unrecognizable sounds, so the processor is working a LOT harder.
If you don't have a recorder, what I would do is solo my synth and sample the sound to tape (cassette) and then re-sample it back into the mpc. If you have another sampler, just sample it there and re-sample it again (to skip the cassette part).. I'm cheap, and I use what I have to do what I need!

If you do have a recorder then simply record it there and keep layering it. Real synths are the schyt. I sold my motif ($2000+) and my proteus 2000 ($1000) and use my novation ($150) and my yamaha dx-100 ($45). You will never get bored of a synth that your comfortable with, the sounds are unlimited, but tritons/motif's osund great for a little while.. in no time, you'll be saving cash for expansion cards!