How can I plug in my line 6 wireless to the back of kemper in my Rackmount rig?

In the Output/Master Section:

Input Source Select

The high-impedance ALTERNATIVE INPUT is located on the Rear Panel. You may find it useful in rack setups, either for connecting the instrument directly, or through a wireless receiver. It is a bit noisier than the FRONT INPUT, but this is only an issue for guitars with a soft output level, applied to heavy distortion. Even when Input Source is set to “Alternative Input”, it won’t work when a cable is still connected to the FRONT INPUT. You can still use Loop Mono when using the ALTERNATIVE INPUT, but avoid using the Loop Stereo; it uses the ALTERNATIVE INPUT as the right return input for the loop, and the Profiler does not automatically compensate for this situation.

As stated the Alt Input is noisy, drive me a bit nuts. Instead I drilled a hole into the blank plate of the mounting kit and run a right angle cable thru to the front input of the Kemper.. Plenty of room to close the rack up with the cable still attached.

To use an external wah you'd either need to run it in a loop stomp or get an expression pedal. I'd go with the midi expression pedal, you can use it for so much more than just wah and the wah's in the Kemper are pretty good imho.

You could connect Wireless to Wah to KPA using either input to use your wah, but the wahs in the KPA are very good.

@DonPetersen - do you have the settings for a Morley wah?

An alternative option would be to pick up a small pedalboard - something like a Pedaltrain Metro 16 or a Templeboards Solo 18. This would give you room to mount your wireless, a power supply to power the wah and the wireless, and possibly a future pedal or two or an expression pedal. You could also use a small MIDI controller or footswitch-style controller (like a Disaster Area DMC or a Tech 21 MIDI Moose) to control the Kemper.

Yes, this means you'll have a pedalboard you'll need to power and run cables to. However, it'll be small. If you're worried about cables, you could always build a snake with a MIDI cable, power cable, and guitar cable with some flex tubing (I like the stuff Pedal Python sells), and make setup quick and easy - just connect to the appropriate places in your rack or set up a patch bay.

Mine's set up with the wireless under the board, but I have an A/B switch to switch to a wired connection (if I'm lazy about batteries or my pack dies). You don't have to go that far, but bring an extra 10' cable to a gig and you're prepared for whatever happens.