What exactly are you trying to setup?
The KPA has a very basic mixer inside that allows you to mix your guitar signal and an external signal from the alternate and return jacks. This is a stereo input so if you're bringing in a mono signal you'll need a special cable to get both ears working from the headphone jack.
you then monitor the entire mixed signal from the headphone jack.
Is that what you're trying to do?
sean
Just let the soundman send you the mix you want to either a wireless pack or if you like a wired system, that's their job 
MC
You could do this even without any additional gear. Feed the signal from the desk into the return and alt. Input jacks and mix it with your KPA using the aux level. Take the headphone out as a feed for your IEM's.
Yes, you need to use 2 mono signals then, otherwise there will be only sound on one side.
You'll need a cable with with single mono connector on one end (monitor send from board) and a cable with two mono connectors on the other end (Kemper alt in and return). You'll get the exact same signal in both ears but at least it will sound and feel better than only having signal in one ear.
Actually I am using a Fischer Amps In Ear Amp 2. Perhaps a bit over the top but it works like charme.
