I've got a lot more work for this project - but I wanted to post what I have so far in case anyone else is interested in the code.
I started with the Arduino library at https://github.com/davedarko/GBPrinter- which looks like it's based on an earlier AVR project - http://hackaday.com/2010/10/08/game-boy-printer-usb-cable-and-software/
The library itself need some serious help to make this a "real" library. Right now - pins are hardcoded, the examples don't work completely, among other things.
So - if you'd like to get this working for yourself - here's what you need to do:
- Download the library from Github and put it in your libraries folder.
- Crack open GBPrinter.h and change delayMs to 60 instead of 20
- Connect GND, and the IN/OUT/Clock pins from the printer to your Launchpad
For more information, hookup, etc - you can find a lot on google - but I found this page very helpful - https://milesburton.com/Gameboy_Printer_with_Arduino. There is a download at the bottom of the page for a word doc.
From there - the example "GBPrinter" will work for a single "block" print (16x20 pixels). Open the serial monitor and send a single "h". The serial setup is a bit odd - so here is a slightly modified version where you see a bit of debugging on startup. 
GBPrinter.ino 6.23KB
0 downloads
I've got a few more sketches - one including the 43oh logo - but apparently Google Drive didn't sync them, so I'll have to grab those tonight and post them.
Dave Darko's site has some image conversion functionality - but I can't get the applet to work. There is also a PHP site on the github repo that does something as well. I wrote a c# converter that I'll be cleaning up and posting later.
My goal end-project is an internet-connected printer - probably something along the lines of an inspirational quote/image-of-the-day for people who visit my desk at work.
And here are some pics as proof 
