Joe Grand recently did a cool Gameboy Printer hack and discovered a compatible Gameboy Printer paper style. It has been mentioned before, but the key to the title is 'Taxi'.
Here is a link on Buy.com
http://www.buy.com/prod/pm-taxi-rece...216676387.html
with the title "PM Taxi Receipt Thermal Roll Paper - 1.5" x 40ft - 10 / Pack - White"