In your case, you just call the lcd update function periodically. In each call, update the buffer and write to the lcd.
Let me expand a little bit. Let's say that your display buffer is vBuffer="Display Buffer123!" initially.
1) display vBuffer; Display shows "Display Buffer123!";
2) left shift buffer by 1, and display shows "isplay Buffer123! ";
3) left shift buffer by 1, and display shows "splay Buffer123! ";
If you do it quick enough, it appears to the user that the string is being pushed left off the lcd -> scrolling.
With that approach, you can do more complicated effect, like exploding strings, string compression, etc.