For me, to do justice with a slider for brakes, I have to let go the stick and use 2 fingers. I hate it.

Use a curve mix to set it up. Use the gear switch to turn it on and off. Mix elevator to the brake channel. No trim, no includes no D/R or Expo, etc. Set the curve points on the Up elevator side to -100% (full off). Set the first point past neutral on the Down elevator side to -100%. Ramp the remaining points up to +100% or to wherever it makes sense. You'll have to adjust the mix to work whatever your brake device is correctly. You may want to ramp up from elevator neutral depending on the feel you want. Depending on the brake unit, It may only have to be somewhat negative on the Up side of the mix.

Devices like Jetronics valves can be set so they engage with slight down elevator and full on just before full down. You can adjust the curve mix accordingly.

You want some leeway on the down elevator side without engaging the brakes so that you can release the stick to neutral after touchdown then push into the braking. Or, to not use air in the traffic pattern if air based brakes. For me it has a comfortable, natural feel to it. No fumbling around, full control of the jet.

I've done literally thousands of landings with down elevator brakes and all the bad things people tell you will happen don't.