So I was thinking...
I don't remember how Essentia actually worked, or how Incarnum actually worked per se. I know it emulated items and abilities, but as of right now; I don't have a clue how it worked.
But...
I was thinking that you could model it with something like Martial E-classes, or non-encounter psionic classes.
The Martial E-class style wouldn't have any dailies, but have very flexible at-wills that get stronger when you put an essentia point in it, and you can only put one point in any one power. So let's At-will X does something like maybe 1[W] + mod, but with a point of essentia, it does the same but with maybe an effect, or even just doubles the damage. The single, multi-use encounter power, makes it so that any power you use has basically two essentia in it, most likely giving a scaling bonus to damage and effect. Here's where it's different over all, the utilities. Like a wizard, you can learn two utilities when you learn any utilities. You then can invest a point of essentia to use be able to use a utility you didn't... prep.
The psionic style would pretty much be the same, but would have dailies instead that would de essentia your essentia'd powers until you had a short rest and no boosting encounter power.
So if this doesn't work to emulate it, I'm sorry; I don't really remember how it worked. These are just some thoughts.