Putting a 2D line on a signal layer is dangerous, in Pads it will not be recognized as an electrical element, so if you cross existing circuitry the verify design utility will not flag it as a short, but when you create gerbers it will be etched along with the traces and you will have a short - 2D lines in decals don't do this, they are converted to silkscreen.
I was looking for this feature of PADS few years ago and I'm afraid it has not been added up to now. I started from PADS2005.2 up to PADS9.2 and the object properties i.e. imported objects from a DXF file don't have the option to be converted into a trace/route.