I dont know how to adapt addblock.ini to do this but how about adding an extra layer of security in this regard to your setup.....http://www.mvps.org/winhelp2002/hosts.htm
Using this will stop any browser (ie/firefox/safari/opera/chrome) or messenger (live/skype/etc) connecting to any bad sites and any in-page links to adverts will be stopped too if their dns address is included in the hosts file.
(typically I see online newspapers with holes in the web page where they obviously had a bad assed link).
I have heard that using this does the same job as addblock, but obviously better via hosts file because it blocks any communication with bad sites not just via your browser - for instance a virus gets on your computer and wants to call home, if its home is in the hosts file it cant.
If you want to try it just download the zip file there ( look for this bit - Download: hosts.zip [right-click - Select: Save Target As] ) , where ever you downloaded it on your hard drive, right click and extract the zip, inside the hosts folder for windows XP double-click on the mvps.bat file, for Vista or 7 right click on mvps.bat file and run as administrator. Once that completes, the extracted hosts folder can now be deleted. The hosts file zip is updated once a month so just re-do for the update.