HHT and how to plot the Hilbert spectrum
I figured out an answer.

From here:
https://web.cs.dal.ca/~tt/CSCI690611/papers/HHT.pdf

The Hilbert spectrum x(t) is:



where "a" is the instantaneous amplitude of the resulting IMF's 
(i.e.: absolute value of the Hilbert Transform applied to every point of one IMF),
and "w" is the instantanous frequency of the resulting IMF', calculated from the inverse tan of the imaginary divided by real components.

So adding the results using all the IMF's should provide the 3D time-frequency-amplitude information.