Could you please describe your current problem in a bit more detail? Perhaps a list of steps you take and what exactly happens now (or even video) with description of what you want to happen instead. I kinda have a suspicion that what you are asking for won't fix your problem (if I understand it correctly) :)
With "always on top" the behavior would be:
1. You can hide the main 3ds Max window behind others & the color picker will still be visible on top
2. Whenever you click anywhere in the color picker window (including the eyedropper tool), the 3ds Max window will automatically come to foreground, obscuring other windows again