Multipass rendering. Something like:
Start of loop
Show everything
CameraClsMode cam,True,True
Hide light1
RenderWorld
CameraClsMode cam,False,False
Hide light2
Show light1
RenderWorld
End of Loop
Start of loop
Show everything
CameraClsMode cam,True,True
Hide light1
RenderWorld
CameraClsMode cam,False,False
Hide light2
Show light1
RenderWorld
End of Loop