Color kinect output by depth

Hi guys,
I’m trying to color a kinect pointcloud based on depth.

Say I have a matte TOP, with the kinect depth on input 3, a red color on input1 and a blue on input2. The matte TOP would change the blacks from the kinect input to blue, and the whites to red.
Is there a way to achieve multiple color cycles in-between, like the ones in the ramp TOP?
td14.jpg

I managed to find a solution to the first problem by using a lookup TOP. I am now facing another issue:
Using the point sprite material allows me to customise the shape of the sprites in the point cloud, but I can’t change the color for individual points.
Using the phong material would allow me to map the desired texture on the point cloud, but I lose the ability to change the shape of the points.