HTP for LED Colour

the ML has color pallets you select the fixtures you want, [COLOR] C1 - C24...  it does up to 24 intelligent lights ok if all you need is a few set and forget looks.  Anything more complex, and then the Element is your friend.  If you want colors per ch, recording subs containing just R, just B, Just G to color mix would be how I would approach the situation...

If you do a lot of work in the programmer on the ML, I ended up having to record a sub that had no color properties in it to help me get away from what info was in my subs to get back to working in pallets.

No, SmartFade ML can't do HTP control of colour. Intensities are HTP and everything else is LTP.

However, you're probably complicating things a bit more than you need to.

Just show them the colour palettes - "Pick lights, press [Color], press the button that's lit in the colour you want"

The only way to 'force' the Smartfade in to running parameters (in your case colour) as HTP values that I've found is to patch them in as standard intensity channels.  You will no longer have access to the moving light controls for those LED fixtures.  I will usually run small events like this if we have a couple of LED fixtures and just need quick access to static colours nothing fancy, patch Red to channel 1, Green to 2, Blue to 3 etc, and just use the intensity sliders to set colours.  It sounds like this is what you're looking for but again you will lose access to the moving light functions.