Thanks for the explanation. In that case you might want to use a "Plain Object" instead of a planet.
The image map shader is in the colour shader set of nodes within the Create Shader options when you right click on the node layout pannel, and the Red/Green/Blue to Scalers are in the Convert set within the Create Function.
Position the image map shader with the same x,y,z and x,y sizes as your plain object, and use the 'project x,z' option.
The more resolution you have in your bitmap, the better the displacements will look, ie more shades of R/G/B to deifine your slopes.
Good luck and have fun.