Chuck, we (University of Wisconsin-River Falls) had one such adjunct research
professor a few years ago.  Guy brought us an NIH grant, needed a home.  It
worked fine, no problems.  I was concerned at the time that his salary was
considerably above university scale--all budgeted from grant funds, of
course--but either no one else knew about it or cared.  Good luck.

Bill Campbell
Director, Grants & Research
UW-River Falls