I haven't tried tried using Robot to control a VM from the host computer, but we do have Robot installed *on* some of our VM images and it works fine inside of those. My guess would be that you're not going to be able to manipulate a VM from the host computer since its basicly a whole other instance of Windows.
.. this information just received in email. Perhaps there are new features to research. I've also attached this to a related VMWare topic in the general forum and will update each with final information if anymore is forthcoming.
1. NOTICE: 1st IBM Rational Testing Tools User Group meeting in Sydney, Australia
From: "Paul Downes" <Paul_Downes@providian.com>
Automated Configuration Testing with TestManager and VMWare -
Sandra Arps, IBM Rational
In this presentation we show how IBM Rational TestManager now
leverages "virtual machine" technology from VMWare to simplify and
accelerate the management and execution of manual and automated tests
across diverse test configurations on single or multiple machines.