You first need to edit the /etc/sysconfig (or /etc/rc.conf, see rc.conf(5)) file in the last section to change the following variable to YES:
# Set to YES if you want ibcs2 (SCO) emulation loaded at startup ibcs2=NO
It will load the ibcs2 kernel module at startup.
You will then need to set up /compat/ibcs2/dev to look like:
lrwxr-xr-x 1 root wheel 9 Oct 15 22:20 X0R@ -> /dev/null lrwxr-xr-x 1 root wheel 7 Oct 15 22:20 nfsd@ -> socksys -rw-rw-r-- 1 root wheel 0 Oct 28 12:02 null lrwxr-xr-x 1 root wheel 9 Oct 15 22:20 socksys@ -> /dev/null crw-rw-rw- 1 root wheel 41, 1 Oct 15 22:14 spx
You just need socksys to go to /dev/null (see null(4)) to fake the open & close. The code in -CURRENT will handle the rest. This is much cleaner than the way it was done before. If you want the spx driver for a local socket X connection, define SPX_HACK when you compile the system.