It is not so easy with the Scott Edwards LCD Serial Backpack. The input signal is inverted (that is more complicated than just sending ~char instead of char) so you have to:
a) use an hardware inverter, or
b) use a NewSoftSerial library which enables to invert signals.
Moreover, the LCD is quite sensitive to precise timing and good initialization.
My working example can be found here:http://ap.urpi.fei.stuba.sk/sensorwiki/index.php/Serial_LCD_by_Scott_Edwards_and_Arduino