If you looking at the original site of nuelectronics on this link you can see wich pins are used and wich not. I already use this shield on the arduino 2k9 and with seperate wireing on the seeeduino mega with modification on the libaries.
http://www.nuelectronics.com/download/projects/Nokia_3310_lcd.pdf
Unused are Digital 0-6 and the digital Pin 12 and already analog 1-5