
Here's the one that I used:

# @(#)$Id: MH,v 1.7 90/04/06 09:44:31 sources Exp $
# SCO 3.2.4v2
bin	/usr/local/bin
bboards	on
etc	/usr/local/lib/mh
mail	/usr/spool/mail
mailgroup	mail
ldoptlibs	-lsocket -lcrypt_i
mandir	/usr/man
cc	gcc
ccoptions	-traditional
manuals	none
chown	/bin/chown
mts	sendmail/smtp
pop	on
debug	off
sharedlib	off
signal	void
sprintf int
options	ATTVIBUG BIND DPOP DUMB RENAME SOCKETS SYS5 SYS5DIR VSPRINTF FCNTL MHE MHRC MIME MORE='"/usr/bin/more"' POPSERVICE='"pop3"' RPATHS FOLDPROT='"700"' MSGPROT='"600"' SBACKUP='"\\043"' SHADOW
curses	-lcurses -ltermcap
ranlib	off

You may want to use a different locking style; my mailbox is mounted over NFS
so I use fcntl-style locking.

I also applied the following tweak to sbr/makedir.c:

*** /src/public/mh-6.8/sbr/makedir.c    Tue Dec 15 10:55:22 1992
--- sbr/makedir.c       Tue Apr 13 14:02:04 1993
***************
*** 24,30 ****
  #include <sys/types.h>
  #include <sys/stat.h>
  #endif        /* SYS5DIR */
! #if defined(SVR4) || defined(ncr)
  #include <unistd.h>
  #endif

--- 24,31 ----
  #include <sys/types.h>
  #include <sys/stat.h>
  #endif        /* SYS5DIR */
! #if defined(SVR4) || defined(ncr) || defined(SYS5)
! #define MAXPATHLEN 1024
  #include <unistd.h>
  #endif

That took care of everything but the man pages, which I installed by hand.

Good luck,
-- Steve