There is no documentation (or I couldn't find any) for the file format of Microsoft agent caharacters. Because of that, seems there's no easy way to convert ACS file format to AAL to use inside Office Assistant package.
I could convert four Microsoft characters to actor libraries by capturing the screen . However, Microsoft warned me to remove them and even their images from the site. Recently, I found those actors available to download at http://dan22.free.fr/Divers.htm.
Greetings,
Kambiz