updating /usr/bin/emacs

[Brian Brooks]

Hello.  I am currently running OS X 10.5.5.

I use emacs within Terminal.app by running the command 'emacs' which
launches /usr/bin/emacs.  Though, this uses GNU Emacs 22.1.1 (mac-
apple-darwin, Carbon Version 1.6.0) -- which is the emacs that the MBP
shipped with I presume.

I would like to update to Emacs 22.3 (or whatever is the latest).
Although I don't want to install a duplicate copy of emacs.  I've
noticed that by installing emacs versions like Carbon Emacs or
AquaEmacs seems to just install a separate copy of Emacs with a GUI
and all that.

I would just like to update /usr/bin/emacs to whatever the latest
version of emacs is and still be able to run it within Terminal.app

How do I go about doing that? Thanks!