Sorry for the delay. Here is the simplest electric brewing wiring diagram I could think of. I am not an artist! The wires outside the box are inside cords in case the drawing creates any confusion. In this scenario, I'm using a 40amp SSVR from Auber Instuments. The website actually shows a wiring diagram for just the SSVR and rheostat to get you started. Get a metal box big enough to add the relay and the heat sink. I think together they are about 6 inches tall in combined height. So you'll need at least 7 to 8 inches of height. It might be better to have a small exhaust fan to help dissipate the heat from the heat sink, but that adds complexity. The easiest option would be to mount the heat sink outside the control box through a hole so that it's still attached to the relay. theelectricbrewery.com has good pictures of this on their build.
Pick up a drier cord from a hardware store and securely attach it to the control box with a 1" wire lock. These are the things that lock all your wires to your house's main panel if you want to see what they look like. A 30 amp 3 wire setup has the 2 hot wires (red and black) and a ground wire (green). In case you are wondering why there is no white neutral wire, in 220v setups, each hot wire uses the other hot wire as the neutral. This allows for 4 times the wattage than a simple 110v setup. More modern 220v appliances require a 4 wire cord because some of the features of the appliance need only 110v. But let's just stay with the 3 wire setup for now to keep things simple.
edit: I think some 3 wire drier cords actually have a black and a white wire (instead of red) for the hot wires and a green for neutral. The 4 wire appliance cords have black and red for hot, white for neutral, and green for ground. It really doesn't matter as long as you know what each wire is for in your cord and that the connections are consistent throughout the system (ie. attach white to white, black to black, etc.).
Connect either the black or red wire from the drier cord to one of the load screws on the relay. Run another wire (10 gauge, preferably the same color) from the other load screw on the relay to one of the hot wire screws on the outlet for the kettle power cord. The other hot wire from the drier cord runs directly to the other hot wire screw on the outlet for the kettle cord. The third wire of the drier cord is the ground wire which is very important. You should run that wire to a screw or bolt attached to the control box so that the entire box is grounded. Then from that point, run a green 10 gauge wire to the ground screw on the outlet for the kettle cord. Run another wire (16 gauge is probably plenty big) to the ground fork on the rheostat.
Run two 16 gauge wires from the other 2 screws of the relay to the Number 2 and 3 pins on the rheostat.
For the kettle cord, get the Hot Pod element enclosure from BrewHardware.com. It's the easiest way to connect the wires and ground to the heating element in the kettle.
That's it! If you want to add more safety features and get more complicated, read my previous posts on the subject. As long as you have everything grounded, this would be a relatively safe setup. Of course, turn the rheostat to 0 and unplug everything when not in use for added safety.