I did it before but never with the Sony to a T3 so you may be walking on new ground. But that statement from their site is also designed to eliminate or support the lack of tech support for the device so that they get paid for helping solve a problem for the other device? Typical disclaimer.
I had two different machines running on a Win98 machine sometime back so I wouldn't worry too much. And I have had tow PalmOne (Palm devices actually) running at the same time on one PC.
If you are comfortable with editing the windows registry....we should be able to get you there but I don't think it will be necessary but again - caution alert - I've not done exactly what you are attempting to do.
edit: I'm going to bed and if you are on the East Coast - you should already be sawing logs. 
