Once you have DreamPi downloaded, flash it to your Pi's SD card via your method of choice. Once it's finished flashing, put the SD card back in the Pi and boot it up. If you're using Ethernet, you'll all done with the Pi side of things. If you're using Wi-Fi, you'll have to configure that on the Pi (Username: pi, Password: raspberry)

Now that the Pi is set up, you'll have to make a Line Voltage Inducer (LVI). The LVI adds voltage to the phone line, so the modems can use it. To make your LVI, cut open the phone line. You should see a red wire, cut it and strip the insulation off. Next, take your power supply, it should have an output somewhere within the range of 12V 500mA. Cut the end off the power supply, then solder the negative wire to one end of the red wire you cut, then solder the positive wire to the other end of the red wire.

Now that you have your LVI, plug the LVI into the wall, then connect the phone line to your USB modem and your WebTV. Make sure both of the lights on your USB modem are on, then power on the WebTV. If it asks if you've moved, say yes (unless you want to dump the hard drive, in that case turn the box off and make an image of the hard drive before continuing). WebTV should dial into the server via a "toll free" number, then dial again, this time showing you the number that's being dialed.

All done! You should now be able to connect to WebTV Redialed.