I really think that doing any of the Berkeley r* commands for any OS at
this point is a Bad Idea. The basic authentication mechanism of those
commands is based on IP addresses, and DNS names. This mechanism is known
to be very weak, and subject to any number of clever attacks from remote
places if you are foolish enough to use on the Internet (a friend of mine
was the target of one such attack, alas, successful). For this reason, no
site that wants to call itself secure will have those servers running
(rshd, rlogind, etc). The only mitigator to these risks would be if your
MacRCP were useful only with Kerberos (or an equivalent
crypto-authentication system), and not with the older "IP address"
authentication that Berkeley CSRG did originally.

On the other hand, the filesystem namespace mapping question is
interesting, so please don't let my opinion of your end project goal
dissuade you from coming up with a good answer to that problem.

Erik Fair