Joe,
Flexwatt is actually very easy to wire. I am having a hard time visualizing what you are trying to do exactly but I can clarify a few things for you until you can drop me a line.
1. If you want to wire two dimmers, you will need two plugs. You can snitch plugs off any old electric appliance you have in the house. (I just cut the plugs off the heat pads I was tossing out and reused those.)
2. I am not sure what you wanted foil tape for. I always use electrical tape for anything I have to do with flexwatt. This can be picked up at home depot/lowes/hardware store.
3. Ok simple wiring lesson #1. Figure out how long you need your flexwatt to be. Cut it to size but when you are cutting, cut between the black wires in the middle of the tape. This means you have to cut in a zig zag pattern. Next, place a piece of electrical tape over one end of the flexwatt. This covers up any bare ends. Take one of your clips, and crimp it over the silver part of the flexwatt on the other end. Make sure you crimp it good. Then repeat this process with the other side. Next you take, your plug, place one of the bare wires through the loop in the clip, then crimp the loop to hold the wire in place. Repeat with the other side. Now what I do next, is being very careful not to touch the metal parts, is plug the flexwatt in to see if it is working. If it doesn't start warming up, unplug it and recrimp the connections. If it does start warming up, then unplug and we will proceed. Next you take the plastic covers, make sure that you have them both going the same way, and place them over the clips. Here you have a choice, you can either wrap the plastic covers in electrical tape, OR you can fill them with silicone. If you fill them with silicone, they are waterproof. I prefer the silicone method, because it looks better too. Then place a piece of electrical tape on the flexwatt, between the two covers. This covers any bare wires that you may have nicked when you were cutting.
While your silicone is drying you can wire in the dimmer. To wire the dimmer, look at your plug wire, see how there are two sides to it, cut one of those. Strip the rubber off the wire, and attach those ends to the ends inside the dimmer. Make sure that you cover all bare wires with electrical tape, as well as the plastic covers that come with your dimmer.
This is flexwatt 101. 
If you have any questions or if you are ready for Flexwatt 102, that offered via e-mail. hehehe.
