WarrenJ
Bill,

If you are concerned with the signal for the DSL line only; then I would do the following:
Go to a big box store (Lowes or HD) But some Category 5e cables by the foot. They will also have the jacks needed to terminate the cable at the modem end of the run.
Install the cable from the outside box to the modem. Attach the blue pair to the screws in the box that has
the signal coming in. You should see other wires attached (maybe red and green) .
At the modem end, attached the blue pair to the jack you bought and you should be set to go. No need to rewire the entire house.