Thanks Kevin, I'll take a hack, that worked great!
Since I want to be able to click on the polylines individually and have them highlight, or change colors, etc., would you say that creating a polyline collection object is the best way? I personally like how clean it would be to just integrate the polyline json object into the czml data source, but that seems to bind the polyline to the billboard automatically. Therefore, when I click on a polyline, it's no different than if I'd clicked on the billboard, and I can't manipulate the polyline individually.
Again, thanks for any advise you have.
David