I am writing "HOW-TO install and integrate ssh on Mac OS X" ... (Where can I publish it?)

[Sergio Gelato]

* Scott Burch [2003-12-03 11:26:49 -0600]:
> As a matter of practice never intermingle your contributed binaries/code
> with system provided binaries. If you are installing binaries that
> already exist in the OS then you should place them in their own distinct
> directory tree (e.g. /opt/local, etc.). If you replace system binaries,
> then future OS updates will indeed overwrite your changes.

Seconded, except for /opt/local which should be /usr/local. Note that if you
used a package management system like fink (http://fink.sourceforge.net/) you
would end up having your ssh in /sw/bin (and sshd in /sw/sbin), or in
whatever location (/opt/OBSDssh, /package/*/openssh, etc.) your package
management system specifies.

As for overriding /usr/sbin/sshd and other daemons:
in MacOS 10.3, sshd is under xinetd control so you can edit the pathname in
/etc/xinetd.d/ssh (or remove that file to take it out of xinetd control).
It's a configuration file, and therefore likely to survive system software
updates.
More generally, MacOS X system startup scripts in /System/Library/StartupItems
can be overridden by locally installed entries in /Library/StartupItems. Just
give your custom script the same Provides parameter as the one you wish to
override. In 10.2, for example, you could simply copy the StartupItems/SSH
directory and edit /Library/StartupItems/SSH/SSH to use your sshd.