In max go to Tools > Channel Info, then copy id 0:vc and past it over -2:Alpha - that will copy your vertex color values to vertex alpha. Afterwords right click on your vertex color channel and clear it out so you aren't storing the extra data.
Using 3ds max 2011 and I would like to create terrain that I deform and paint vertex color at the same time. Basically, as I create hills I want the vertex color to go from black to white depending on the height of each vert. Found this tutorial (link) that does what I want it to do, but I'm using a custom material at work…
Can't you use a displace modifier then take the vertex colour as the displacement map. This means you can also vary the overall height. edit: Just checked the tutorial and that should be fine as you can apply the material ontop of the vertex colour and so see the results.
That's how the tutorial had it, but the custom material I'm using doesn't have a displacement maps (it's a proprietary plugin material). So I'm trying to find a different method (maybe a modifier that changes the vertex color automatically depending on the modifiers' gizmo). Thanks.