Here's how I do it:
Options +SymLinksIfOwnerMatch
RewriteEngine on
RewriteCond %{HTTP_REFERER} .*.fusker* [NC]
RewriteRule .*\.(gif|jpg|jpeg|bmp)$
http://www.yourdomain.com/images/hotlink.gif [R,NC]
Works like a charm for me.
P.S. And like another post in this thread %haha123; = the opposite of }