Off-camera Flash: T3i, Yongnuo YN468-II

Pretty much a novice when it comes to flash...but this is what I want to do. I want to be able to use an external flash off the camera without using the pop-up flash. Both in the Canon manual and in the hints on this site, there is mention of using the pop-up flash for signaling but not actually using it's output. As phrased on this site:

"If you have a 600D, 650D, 700D, 60D, 70D, or 7D, you can remotely control the output of many Canon EX flashes via the camera's own wireless flash controller. That system uses the built-in flash to fire pulses of light which tell remote flashes when and how brightly to fire. Since the built-in flash is active in that case, you can have it contribute to the exposure if you want.

Even if you tell the built-in flash not to fire when it's acting as a controller, the control signals might show in the image, for instance in reflections off glass."

I cannot find any way to determine that I don't want it to contribute to the exposure. My flash is ETTL. If I set up the flash menu on the camera as stated in the manual (EasyWireless), it asks for a channel. The flash doesn't offer channels. Additionally, I can only get the flash to respond if I put it in S1 (slave) mode, not TTL. I'm not sure if that is correct or not. Regardless, whether in slave mode or not, the manual says the pop-up flash has to be up....but how can I keep it from fully firing yet still send the control flash to the Yongnuo? I know I could use a cord, or buy wireless transmitters, but I'm thinking I'm missing something and this flash should work wirelessly with this camera. In summary, how can I get the pop-up flash to serve as a master without actually providing a full flash in the exposure? I could easily be missing something simple, but I sure don't see any way......