FontSizer does require a PostScript LaserWriter (which actually does the
work of figuring the pixels in the font from a PS outline description). You can
use any PostScript font, built-in or downloadable.
I was under the impression that the LaserWriter was a "write-only" device, that
is, that you couldn't read back proprietary information such as font character
outlines. Do you know how FontSizer gets around this? If this was easy to do,
you'd think it would be built-in to any computer that needed good-looking
screen-rep fonts.