Have you given something like this a try?
You add a rewrite rule to your htaccess file. Seems to work pretty good so far or at least a good temp fix until you get something a little more advanced.
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !your domain to allow \.com [NC]
RewriteCond %{HTTP_REFERER} !your domain to allow \.com [NC]
RewriteCond %{HTTP_REFERER} !your domain to allow \.com [NC]
RewriteCond %{HTTP_REFERER} !your domain to allow \.com [NC]
RewriteRule \.(gif|jpe?g|png|wmv|flv|swf|mpg)$ h t t p y o u r d o m a i n.com/images/nohotlink.jpe [NC,L]
the last line is an image substitute you can use so when it is hot linked that image shows up.
