I was thinking of Artist's Tool also, but then I realized what he wants is an external program to do this, likely for development purposes, and Artist's Tool unfortunately is useless for such a thing...
This is easily doable then, using just about any Paint program.
Load up the PCE_Colors image, them reduce the palette size to the smallest
that you program can handle whiel still holding all the values.
Then you can export this to a palette.
From here you have several options. You can either load up the palette as your starting point, and work with just that. Or do your image, then import the palette (replacing the current one).
Doing this in PSP is easy (I am guessing it is easy to do in PS too, but I am not as familiar with PS, so I do not know specifically how to do it in that program).
-bt