You can use morphing: set the time to what is needed, volume from 0 to the level you want and use the rig switch to morph
You could use Morphing to increase Rig Volume and/or other volumes.
Morphing can be triggered via button and MIDI control change # 80. And you can set the Rise Time and Fall Time of Morphing per Rig in Rig Settings.
| #80 | Morph Button (value 1-127 triggers ramp from Base Sound to Morph Sound according to selected Rise Time; value 0 closes transaction; next value 1-127 triggers ramp from Morph Sound to Base Sound according to selected Fall Time; if option “Momentary” is selected, value 0 triggers immediate return to Base Sound) |
Your footswitch needs to be able to send a MIDI control change. If it is and how to set that up should be described in the Tech 21 manual.
Simply use a MIDI footcontroller, which can do it. There are inexpensive solutions like Behringer FCB1010 with Uno4Kemper or Eureka - or even better a PROFILER Remote.
I'm sorry, but I don't want to buy a new footcontroller for 1 volume fade in. Isn't there some kind of effect or pedal you can put on a preset, so when you press the footswitch for the preset it just fades in?
I've read the midi mouse manual, sorry to say, but this is the cheapest midi controller I've ever seen. no programming no setup only program change from 0 to 127. And that for a price of $ 100.
Every Chinese device is better there.
You can buy a cheap keyboard sustain pedal for $10 to $20 and connect it to the expression port of the Kemper, in the system menu you can then program the expression port to morph.
I advise you to sell this midi controller, any cheap "midi commander" on aliexpress is better.
Thank you for the advice. And I LOVE my midi MOOSE pedal (not mouse). It's definitely not cheaply made and it fits right in my kemper bag with my rack profiler. I don't want any extra pedals as I want to keep it as simple as possible for live use. But if you got any ideas, other than buying things, I'm open 
I think you're in the "guitar volume knob" camp with a budget of zero. I do understand financial constraints and wish there was a way.
Thank you for the advice. And I LOVE my midi MOOSE pedal (not mouse). It's definitely not cheaply made and it fits right in my kemper bag with my rack profiler. I don't want any extra pedals as I want to keep it as simple as possible for live use. But if you got any ideas, other than buying things, I'm open
Sorry, also the "midi moose" can only send program changes (PC) but you need continues controller CC commands to "Controll" a midi paramter. This is not Kemper specific it's a MIDI standard definition. PC for changing Programs CC for Changing Paramter. Your Controler is not able to do that, this controller is also not able to switch a an FX or controll any parameter of an FX. You can only switch between Sound Slots.
Sorry for you. 
Unfortunately, as Yoda Guitar has said, the Tech21 MIDI pedals can’t send CC messages. It has zero to do with the Kemper.
Without that ability, and without acquiring a pedal that does (of which there are many), you’re stuck.
A single button momentary foot switch would not be an expensive purchase.
How long of a volume swell do you need? Can you do it with the volume control of your guitar as you play the part?
A single button momentary foot switch would not be an expensive purchase.
How long of a volume swell do you need? Can you do it with the volume control of your guitar as you play the part?
Exactly what i wrote in post no9: A simple Sustain Pedal or momentary switch will do the job.
You could assign morph to the quick button (have the Kemper handy) and trigger your fade by hand.
