Individual polyamorous persons use the term "polyamorist" to describe
themselves. Besides some on this list see http://joyfulgrl.diaryland.com/ .
Even opponents of polyamory also use the term. Some Christian--and I use the
term Christian loosely--opponents of polyamory talk about the emergence of a
"polyamorist" movement dedicated to "polyamorist rights" at
http://headlines.agapepress.org/archive/1/92006e.asp .