The program setfont will accept font descriptions like

# combine partial fonts
none.00-17.16
ascii.20-7f.16
none.00-17.16
8859-1.a0-ff.16
where the first line is precisely # combine partial fonts and the remaining lines contain filenames for PSF fonts to load. The above example (it is the file iso01.16) describes a font with 256 positions, of which the first 32 are taken from the file none.00-17.16, the following 96 from ascii.20-7f.16, the following 32 from none.00-17.16 again, and the final 96 from 8859-1.a0-ff.16. In this way all ISO 8859-* fonts of a given pointsize (here 16) can share the same initial 160 positions.