MSD 8728 Soft Touch Rev Control Wiring?

They indicate using violet for trigger, seems like it might also work by using white connected to green at coil (-). The 12V supply might be powered from IGN1, blue wire that feeds ballast, and regulator. Do not use coil (+) because the voltage will be dropped by ballast.

I looked at wiring diagrams to figure out, but no experience with MSD units.