My Raspberry Pi came yesterday, so went ahead and set that up. I had a few hiccups setting up KAPCOM, but it worked once I figured those out. I ended up needing some additional software packages:

sudo apt-get install python-pip
sudo apt-get install python-dev
sudo apt-get install python-xlib

With those installed, http://setup.py happily ran and installed the other Python modules. I also set up Synergy for sharing my trackball to my KSP machine. The instructions on Adafruit were mostly correct, but I also had to run the following commands:

sudo apt-get install libcurl4-openssl-dev
sudo unzip ext/gmock-1.6.0.zip -d ext/gmock-1.6.0/
sudo unzip ext/gtest-1.6.0.zip -d ext/gtest-1.6.0/

After this, Synergy built correctly. I configured it so the mouse leaves the Raspberry Pi and never comes back unless you press F1:

section: screens
	KAPCOM-Pi:
	Mac:
		meta = alt
end

section: links
	KAPCOM-Pi:
		right(0,100) = Mac
		left(0,100) = Mac
		up(0,100) = Mac
		down(0,100) = Mac
	Mac:
		# left(0,100) = KAPCOM-Pi
end

section: aliases
	Mac:
		Mac.local
	KAPCOM-Pi:
		KAPCOM-Pi.local
end

section: options
	keystroke(F1) = switchToScreen(KAPCOM-Pi)
end

I also added a startup script to start Synergy and run KAPCOM. I tested it all out and the trackball worked great. KAPCOM is currently in a broken state because I'm still working on the configuration changes for adding multiple modes and Arduinos.

Very happy with the progress I'm making. I'm going to spend some time at lunch working on the mode and Arduino code. Once I get that done, I can go back to working on the enclosure.