Hi.
I am curious about what your recording method is. You say that you use your KP3 to 'record fx over the master channel'
Does this mean that you are re-recording in another channel it as you use it, or that you are recording it as part of the arrangement? Or are you possibly playing out live??
Also, I am wondering about the amount of wet/dry that you use for your kp3. I think it is either 'send' mode or 'direct' mode?
As for hooking it up on the master channel, an option that you have is using the "External Effects" effect that can be found under Audio Effects. What this allows you to do is select audio channels that Live sends out to (3/4 for instance, if your audio card is sending out to the kp3 via 3/4), and what audio channels it will listen to (lets say it is 3/4 again). Then you would make sure that your Master is set to a different channel output (1/2 going out to speakers). In this case, I would set your KP3 to 'direct' which lets normal audio through, and then lets the KP3 decide what fx to play Over it. If you were more interested in using the 'send' mode with the KP3 on the master, then you could hit Ctrl+G to group your External Effects into a rack as a wet, and create a second channel within the rack that is the 'dry' signal. This might require a macro knob to switch between the two.
Another option is, creating the same "External Effects" in a Return channel (with your kp3 set to 'send' mode). There is a fun trick you can do for this that allows you to use the crossfader as your on/off or wet/dry effect for the sending! (if you get this setup to work, I may explain it to you

)
Lastly, if you wanted to get really confusing.. there might be a way to record your use of the KP3 into Arrangement view via MIDI.. I don't want to get into that unless I have to because, I can't think too well at the moment haha.