Normally, I just leave my 3d plotting to gnuplot. That said, it's probably not what you wanted. :-) So I googled a bit, and found a couple of articles that may be of help -- the first, as a rather technical paper, and the second that gives the outline for a class lesson the subject

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2744089/
• http://www.inf.ed.ac.uk/teaching/courses/vis/lecture_notes/lecture7.pdf
• google:algorithm for dividing 3d data into contours

It's at least a place to start for ideas, even if it doesn't give everything you want right away. But if you do get a solution, make sure you at least post an outline, if not all the code; I'd be interested in the end result.