What are proper install.cfg for configuring multiple slices?

[Peter Steele]

>I want to do an automated sysinstall through an install.cfg script and
>the script partition the install disk into three slices. I've been
going
>through various tests trying to figure out what the proper directives
>are but I haven't had much luck, and I can't find any good examples.

After a lot of experimenting, my impression is that sysinstall simply
doesn't support multiple slice installations. It works to a point, but I
get some unexpected errors, e.g.

Unable to make device node for /dev/ad0s1a in /dev

and after the partitioning is complete, there are funky entries under
/dev:

/dev/ad0c
/dev/ad0cs1
/dev/ad0cs2
/dev/ad0cs3
/dev/ad0s1
/dev/ad0s2
/dev/ad0s3

There should be entries such as /dev/ad0s1a and so on, but these do not
get created. I've been unable to find even one example of how to
formulate multiple partitions in install.cfg, but I'm pretty sure I'm
doing it right, based on the sysinstall docs. Does anyone have any
experience with this?