Mapping Center Answer:

I suspect that you are talking about a cross-blended hypsometric tint in the same way that Tom Patterson describes in his article "World Relief Map: Raster Map Art with Cross-blended Hypsometric Tints". This is the link to the full article: Using Cross-blended Hypsometric Tints for Generalized Environmental Mapping.

You can create a custom color ramp and use that to symbolize the elevation. Or you might have better luck with a color ramp so that you can assign the specific colors to the specific elevation values. 

Here is a link to a nicely written blog entry by Simon Woo on how to create a custom color ramp. And here is another blog entry he wrote on how to create a custom colormap file.