Yeah, just create another box and set the polyMode to viz.POLY_WIRE. Here is some sample code that shows how to achieve this effect:
Code:
size = [1,1,1]
box = viz.addGroup()
box.faces = vizshape.addBox(size,splitFaces=True,cullFace=False,parent=box)
box.faces.alpha(0.5)
box.faces.color([0.77, 0.90, 0.13])
box.lines = vizshape.addBox(size,lighting=False,cullFace=False,parent=box)
box.lines.polyMode(viz.POLY_WIRE)
box.lines.lineWidth(6)
box.lines.color([0.24, 0.42, 0])