use Bitlbee (IRC to WLM Gateway)
http://www.bitlbee.org/main.php/news.r.html
or
http://meebo.com
Yes I know you're looking for a way to do it in WLM, oh well
# Windows Live Messenger ad servers
127.0.0.1 rad.msn.com
127.0.0.1 global.msads.net
127.0.0.1 rss.video.msn.com
127.0.0.1 ads1.msn.com
127.0.0.1 rad.live.com
127.0.0.1 specials.uk.msn.com
Yes, paste that in your hosts file...apparently
or
1. Click Start button on Windows
2. Go to Control Panel –> Internet Options
3. Click on the security tab and click on ’Sites’ under restricted sites.
4. Add the url “rad.msn.com” and those ads will never be shown again.
Now prove me wrong CookieRevised
And by prove me wrong I meant don't prove me wrong.