I'm going to be a computer tech next year at my college and I don't want to install Spybot everytime I want to use it. Is there a way to make it run from a USB Thumb Drive to scan the computers drives?

I tried just copying the files over to my thumb drive, but it keeps telling me there are no threats and gets done really quickly so I'm assuming it's only scanning my Thumb Drive. How can I make it scan the computer?