Hi people,
Based on the internal initial code from @JCPalmer, here are the per point colors for LineMesh and LineSystem
var points = [arrayVector3];
var lineColors = [arrayColor4];
var line = BABYLON.MeshBuilder.CreateLines("l", {points: points, colors: lineColors}, scene);
// same for LineSystems
var lines = [arrayVector3[] ];
var colors = [arrayColor4[] ];
var lineSystem = BABYLON.MeshBuilder.CreateLineSystem("ls", {lines: lines, colors: colors}, scene);
Note1 :