Well, there are a couple of ways to go about this.
1) you block off the return on the fuel rails and plumb the regulator in a loop around your pump, like I mentioned above.
2) You bend up a return fuel line the same shape as your feed line. Then either poke a hole in your tank for the return, or you Tee into the fuel line on the inlet side of your pump, and make that your return point.
There are 2 ways you can make a regulator work.
1) Pressure blow off. You put the regulator in the feed side of the line and any excessive pressure is dumped into the return line.
2) Flow restrictor. You put the regulator in the return line and it acts like restrictor to increase pressure, and reduces restriction to lower pressure.
Both ways can use the same regulator as long as you get your ins and outs hooked up right.
Hope this helps. I'm not the best as explaining myself, so if you want some poorly drawn cartoons from paint, I can do that too.
Adam