I have dsl wired through a dry loop in my home connected to a router. I want to use it in my workshop which is about 300 feet away. The only way I can do it is to somehow use my old 4 wire line I had for the telephone, it's ran underground and I can't run more. Does anyone have a good solution?

A device such as this would do the job, but only supports speeds up to 10Mbps. A wireless solution would be better though. You would need 2 access points that support WDS, and a couple high-gain antennas. More Info

Well, actually you only need 4 wires for ethernet. I used a long piece of the telephone cable that's used by the telephone company to run underground from pedestals to houses and put RJ45s on each end and ran Ethernet through it. I'm not sure if it was 300', but it was over 200'. Worked great. The individual strands of wire were actually too thick to fit into the RJ45 with the insulation, so I had to carefully expose just enough bare copper so that the wires would fit into the little slots where they get crimped, but so that the insulation kept the wires from shorting. I'm not saying this will work for you, but letting you know that it "could" work. Cheap to try if you have some RJ45s and a crimp tool. NOTE: the kind of cable I'm talking about is the very tough stuff they use to "shake" into the ground, the wire you have may be the stuff with thinner individual strands, which would be easier to work with.

Do I use pins 1,2,3,and 6? I read that on some wiring help site.

Yes, pins 1,2,3, and 6 are the only active pins in 10/100 Ethernet. The other 4 pins are Unused. Pin 1: Transmit+ Pin 2: Transmit- Pin 3: Receive+ Pin 6: Receive- Just make sure that the RJ45s on each end are connected the same, wire color to pin. Also, get it stright which pin on the RJ45 is #1. I always have to check myself to keep from getting that backwards.