You can work with any font you like, I will use this font as an example:
Open your font with Fighter Factories palette editor.
As you can see, those are the default colors of the palette.
Add the colors you want to the next row of the palette, for myself, I will use the colors of GG XX combo font.
Now, we will aply that palette to the pcx. Make sure that the second row doesn't use the same color, for more control over the image.
Now, as you can see in Font Factory, that my font is already set up. What we will need to do know is change the value of the color depth to the ammount of colors that each bank uses:
Alot of fonts might use more then 16, that doesn't matter since it can use more then 1 bank.
Now for the part where we mess with a .def of your choice: Screenpack, lifebars, and the new character intro feature that lets you use fonts.
in a screenpack, search for p1.name.font or any other thing that uses the font.
p1.name.font = 2,0,1
You will change the number in the middle (0) to any other number of your choice(limit is 15).
And your done. You're resault will be this.
Now that I have wasted a few minutes of your life, enjoy :)