I am having trouble with this. I got it to work kinda but I have a 20x4 display. I am getting sticky characters and areas that don't update as they should. then after a while, everything looks like giberish on the lcd...
Try changing the baud rates, slower would probably be better. Using it with LCDSmartie it does okay, but when I try use it as a regular serial, I can do all the normal stuff for a while.. but then it does what you say, and prints all the extra crap.
I haven't played with it for a while, so you may want to do some experimenting.. but you could try add a small delay after the Serial.getch() or serial.read, whichever. It's possible it's just sending the information too fast so it get's garbled.
You could also try to remove some of the un-used code.. such as the functions I added for reading eeprom/writing to it if you're not using it.
Still not really sure how it's done.. but with LCD-Smartie, it works like a champ, scrolls fine and such.