just a little followup:

i got it working, but ultimately needed to add 1 layer per segment, rather than 1 per group. it looks if you use grouping, geom.Path will always give each group a distinct color (geom.js 229). i believe that's generally what you want, but it happened to not be the right thing here. I probably could have subclassed LABKEY.vis.Geom.Path or something, but it wasnt worth the effort for this one graph. thanks again for the help.