It is possible to stop bots from accessing your site by adding a 'robots.txt' file to your directory. In this file you can specify which bots to disallow and the directories to block them from.
This tells all bots that they are not allowed to crawl your page. If you look at the name of the websense bot, then you can replace the asterik with the name of that bot, and that will prevent specifically that bot from accessing your website. The 'disallow' field is the directory to block the bot from. A '/' means all directories.