XMLHttpRequest Security errors

Hey /prog/, not a regular but I thought I'd try you guys - I'm running into problems when I try to load cross-board content using xmlhttprequest. Apparently it only works in the same domain, so I get security errors when a link pointing to img wants to load content from dat (the cross-board links send you to a redirecting page which does this). Any ideas on how to work through this? I'm running the code through the Greasemonkey Firefox extension. Thanks!

Do you even know how XMLHttpRequest works? Imagine a script which reads a password input element and sends this asynchronously to the villian's web server.