I've made a first cut at an scn.4 man page (I figured I should do the
dirty work, since the driver has my dirty fingerprints all over it).
It's at ftp://alpha.gnu.ai.mit.edu/budne/pc532/scn.4

I think I covered all the salient points, the prose and formatting can
use work.  In the end I got tired of trying to suss out how to get
what I wanted out of the mandoc macros, and resorted to raw troff "br"
commands.  No doubt someone with a clue can fix this and other faux
pas!

-p