I can't get it to work on mine (on unmodified 2238 copy, it still doesn't show the avatars for me), but if you're looking for samples of dialog, it was implemented in 2238 on Tandi, Marcus, and Harold. See their corresponding .fodlg files ( ex: ncr_tandi.fodlg ).
Those .png images are located in Client\data\faction.zip\art\intrface, but I don't think the Server has anything telling them to use those files. There's a INTRFACE.LST file in Server\data\deprecated_lists\INTRFACE.LST, which is obviously deprecated. I'm not sure how to get that to work, a dev would know more, of course.