Using redhat-switch-mail-nox in a script?

[Benjamin J. Weiss]

I'm trying to write a script that'll set up an email server automatically.  
I want to switch from sendmail to postfix on RHEL-3, but I can't seem to 
find any command-line switches for redhat-switch-mail-nox

Does anybody know how to switch from sendmail to postfix with a simple 
command instead of the user interface?  I tried 

redhat-switch-mail-nox postfix
redhat-switch-mail-nox -postfix

but nothting seems to work.  Any ideas?

Thanks!

Ben