Steve , what you want is GPLOMe (GPL Online Messenger) get it here:
http://zoidberg.homeip.net/oldhome/Map any message you want to any keystroke, open your Logitech profiler and map the keystroke to the button of your choice and thats it.
And of course: keep GPLOMe and the profiler running while you are online.
Yep, i used to use that, but that's two extra progs running in the background whereas GPLShift doesn't require anything extra. But processing power isn't in a shortage for most these days.