scroll up text led matrix

hi guys, do you have an idea on how to make the text to scroll up or down?
I followed this thread by hari: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1267391793/0

but my professor wants us to include a button in our circuit that will allow the circuit to print either left/right or up/down. :slight_smile: