I am trying to connect the Canon 550D wirelessly to my computer so that I can control it from at a distance. It can connect normally via a USB cable, so I was wondering if there was a way to plug a dongle into the computer, and a dongle into the camera so the two can connect. I'm basically looking for a really long USB cord that will work over long distances (200+ feet). Another important factor is that I really would prefer not having use a power cord, rather just plugging in a dongle, as it will make the setup more mobile. Does anything like this exist?

(I know that Cables Unlimited had something like what I wanted, but they went out of business last year)