[Lynne]

It's not quite that easy to do what you want. Your username actually gets processed through a function called fetch_musername to determine what is should be displayed as. You might be able to modify that function to do the same for the title (includes/functions.php). It might be easier to just modify the postbit to add the style directly. ie for red admins:

<if condition="is_member_of($post, 6)"><div style="color:red;">$post[usertitle]</div></if>