That in itself may be the issue. Nowadays many colleges block p2p use. How they do it may vary such as blocking ports or blocking particular apps. Yes they can block particular apps.
You said you tested port 6346, was that this quick test:
http://www3.limewire.com:6346/ (if you receive the message Test page was successful then at least you can at least partially access thru that port.) If you don't receive any message on that page or your browser can't get that page then your college is blocking that port.
You can try Forcing IP which sometimes works for college situations:
Force IP instructions & sample image Try leaving LW on for at least an hour to give it a chance to connect. Failing that, you can try other ports to go thru. It could be wise to contact a school network technician to find out if they do block p2p use (& if so, how they do it.)