You can certainly replace a /.rhosts file with a
/.ssh/authorized_keys file, then use either rsync-over-ssh or (if a
simple rcp-style cmd is most convenient for you) scp, which comes
with ssh and looks just like rcp to use.
If desired you can even restrict the authorized_keys entry to only
allow connections from one host, or a short list of hosts, and to
only permit the execution of the server side of scp or rsync. You
can even confine the args so that only specific copies will be
permitted.
I recommend starting with the latest version of OpenSSH (does ssh1
and ssh2 protocols, requires OpenSSL as a prerequisite).
-Bennett
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