Other than the mounting bracket I got from Jack Cotton, I ordered everything else (Gauge, cup, hose, etc) from Summit Racing. They had the braided hose in stock in the correct length (I think it was around 30" or so) and all the other fittings came with the gauge except for the three 90* elbows I needed.
I don't recall the precise size of the elbows but if you take the straight nipple (that comes with the gauge and that connects the gauge to the hose) to any shop that handles piping, you'll be able to match it up easy. It seems like it was a -4 or a -6 but I'm not sure. You'll need two of the elbows to make the 180* turn from off your fuel rail to send the hose back towards the firewall and rear of the hood. The other 90* elbow will be to run the hose vertically downward on the back of the gauge to go beneath the hood. Piece of cake. Just make sure you seal and tighten all connections properly! You do NOT want any fuel leaks.
Also, after installing the fuel/braided line to the gauge, vent the air out of the hose by cracking the connection right at the gauge. Be careful! You want to just let the air escape and not too much fuel. It will not take much venting to do this.
Actually, the hardest part was securing the mounting bracket sturdily enough so that it doesn't bounce when the car is going down the road and the pavement is rough. And even THAT wasn't hard to do, just a little adjustments and so forth. Other than figuring out where to tie in power for the bulb inside the gauge, it was a really straightforward install.