Setting the Metafont mode
To be able to build a PK file, 
needs to know what mode to use.
gets this information from either the printing_mode or
viewing_mode parameter and simply passes the string on to .
For dvips, the mode string is specified in config.ps.
WARNING: The given strings must exactly match known mode_def values
defined in either modes.mf or macmodes.mf;
these files are kept in :Metafont:Inputs:.
It is also important to make sure the current printing/viewing resolution
matches the pixels_per_inch value in the corresponding
mode_def, otherwise won't create a suitable PK file.
's Default config file sets both modes to laserwriter.
You might need to change these modes, either by selecting one of the
supplied config files (e.g., StyleWriter),
or by editing the Default config file.
If a mode string is empty ("") then will use the localfont
mode which is currently equivalent to the laserwriter mode.
Common modes for users are
laserwriter, stylewriter, imagewriter,
ljfour and linohi.
If none of these modes suit your particular printer then look in
modes.mf to see if there is a suitable definition. The most important
thing to look for is a pixels_per_inch value that matches the resolution
of your printer. If you can't find a matching mode_def (unlikely), you
will have to create your own and run INIMF on MakeTeXPK.mf to
rebuild MakeTeXPK.base.
NOTE:
I've set the stylewriter mode_def parameters in macmodes.mf
to be the the same as the laserwriter parameters
(except for pixels_per_inch of course).
This was done so that both modes can share the same set of PK files.
People who are fussy about their pixels (or with better eyesight than me)
might want to optimize the stylewriter parameters for that printer.