When you load the Plasma synth with a default project on a Luna with the 1632 mixer, you will get a "Not Enough DSP" error message. To use the Plasma Synth, simply drop the sample rate from 44.1Khz to 32.2Khz in the samplerate menu from the SPF console. This will leave you with enough DSP for the mixer, and one(!) instance of the Plasma, and a bit left over for a small effect.
This is Drumsynth is massive, so don't be suprised that you can't run more effects or another synth along side it. Just record it and then modify it to your hearts content. If anything it will make you start looking for another Pulsar to marry up to your Luna.
I realise that most people wouldn't want to record in 32.2Khz, but for access to the sounds that the Plasma can make, I'd say it's worth it. If you need to, just resample the recording, though I found 32Khz to be fine - it's still less noisy than trying to direct record my Techstars and Simmons.