I noticed in the past of people talking about color mixing LED par cans on their console. The best way I found out how to do it (on an ION) is to set your LED Fixtures in your console to have all your attributes such as all colors at a home position of zero, not 255. Except intensity, which should be kept at 255.
Now when you select the fixture, your ML control of it comes up and you just one click to a color rather than pulling all of them down from 255. This also gets rid of having LED fixtures on your subs mixing all to full white while changing scenes. Set 3 subs R,G,B and as you slide them up, it will go from that color dim to bright. Hope this helps.