reported as spam as an old post... and it is old, so it's be better to not drag this kind of stuff up... a general rule of thumb is that if it's a few pages deep, leave it there.
anyway... to answer the original question.
no, you can't block a single URL in the hosts file.
but this site will give more help on how to block single URLs whilst allowing other urls on the same server to be seen.
(under the heading "Hosts file problems and solutions" -about half way down the page)