Dual brake servos, 3rd channel mixing?

I have a Spektrum DX3. I also have a Marder with dual steering servos and now I am running dual brake servos, how do I run the second brake servo for my cable brakes? I would like the brakes to work along with my throttle servo, but I would also like to be able to flip the 3rd channel and lock them up. I'm sure I wire it through the Aux channel, but how do I program the radio? I hate JR/Spektrum radios BTW.

I would like the throttle/brake servo to come on a first and be a bit stronger than the front brakes. I like to have a little slide on my turn in, but I need to he the front come on when I really need to stop suddenly, so I guess I want the rears to do most of the braking, but if I get in a "Oh Shit" situation, I need the front to kick in past 3/4 brake travel. So how do I do it?

The 3rd channel has to be seperate, so I can do cool bleach box burnouts without having to brace it or pull it up to a curb. It's more of a novelty, really than anything else. I need the front brakes to work off the trigger though. So they have to work both off the brake trigger and the thumb clicker for the AUX channel.

Sorry I covered the same thing a few times, but I wanted to make sure everyone understood what I was asking so I didn't get asked, "What do you mean?" Or, "Are you talking about this?"

Thanks for the help...