using multigram in rc.locals

I've got some recipes that I'd like to know if we're dealing
with a list subscriber, so using multigram comes to mind.
The only multigram documentation I find is in the manual, 
section 6. "Multigram and the thresholds in rc.init/rc.custom"
which gives one example of calling multigram, and a brief
description of its output.  Is there any other "man multigram"
sort of documentation I should be looking for?

Looking in the source for multigram.c, I see some documentation
output from a case statement, which looks like clues as to the
options, so that's a possibility for understanding the invocation.

For understanding the output, it'd be nice to run multigram on my
home machine.  I have the Smartlist sources, but I haven't done a
real install at home, because I run Smartlist on my ISP's server.
Typing cc multigram.c gives lots of errors regarding missing includes
and such, so my next question is, is it possible to play with
multigram without doing a full Smartlist install?  I don't see a
makefile anywhere in the sources, but maybe one is generated by the
install.sh scripts. 

I can probably use egrep to do what I need to do in my rc.locals.  Am
I wasting my time trying to learn enough about multigram to use it?
Do I need to use egrep to use the output of multigram anyway?  Or
does it produce a true/false exit status that I can use directly in a
procmail recipe? 

Of course, there's the example in Smartlist's rc.submit; I can copy
it and hope for the best, but I'd prefer to understand a bit more of
what's really going on.  I hate to do much testing on my real list
without some beta work offline at home. 

FWIW, my ISP uses the ancient procmail 3.10 and its Smartlist.
The manual section 6 seems to be identical for procmail 3.13/SL.

TIA,

Jim