Sorry I wasn't more clear. The code I gave before was from an addin that was called after the user had created and then selected a shape. In your code, you don't need to select it, you just need to grab the reference to the Shape object that is returned when you do the addline, then change the properties:
Code:
Set objshape = objmap.Shapes.AddLine objloc0, objloc1
objshape.line.ForeColor = color
objshape.line.Weight = 1