Cloning R Installation Across Multiple Computers

I would like to set up identical R installations, with the same packages,
on multiple computers and with minimal interaction by users. Ideally, I
would like to have an installation script that the user can just run that
will set up everything, including R itself and base packages.

Standard packages would need to include ggplot2 and its dependencies, Rcmdr
and its dependencies and some Rcmdr plug-ins. Best of all would be to have
the script include JGR and Deducer in the installation. This would be set
up on Windows XP 32-bit, and all packages have to install from local .zip
files; R cannot get to the package servers through our firewall.

I could do the setup once, manually, on one machine, but I'm not sure if I
can simply copy the R installation directory to other computers and have it
still work. I don't think that the Windows registry wouldn't be configured
if I did it this way, and I'm not sure that JGR would be correctly
installed. Another approach would to have the user install R, then copy the
R directory tree from another computer that has been set up, and finally
JGR would have to be installed by the user. I'd like to roll this all into
one, simple step that the users don't have to worry about screwing up.

I recall that there has been some discussion of this on r-help in the past,
but I seem to be using the wrong search terms as I cannot find anything.
Any suggestions for, or pointers to, solutions will be much appreciated.