Im not an expert on this thing but as far as i know MSN uses port 1863, but if it cant connect (possibly because the port is blocked) it will automatically try to use port 80 which is used by internet explorer itself so they wont be able to block it 😉 (Correct me if im wrong)

My school limits downloading of certain files so i have zipped up my messenger folder, renamed it to a downloadable file type and downloaded it and it works fine. Give it a try http://www.msndownload.da.ru and when you get the prompt to save as choose to save it as a zip file. Then just unzip it to where ever you want it and it should work. Let me know if anyone tries this, its worked for everyone here 😀