(Shameless bump.) 
Does anyone know if this is possible? On a related note, customized headers from one group are sometimes appearing in groups beyond the control of the owners in question. It almost looks like a caching bug, as these customized headers will sporadically appear in other groups on some visits by other users. We're running 6.1.0.23780 but intend to upgrade to 6.1.10 this spring if not 7.1.