DfRobot provides the simplest way to get started with LiquidCrystalIO on Uno and Mega (and other compatible boards). It has a display with an array of switches connected to A0 (up, down, left, right and select). This library works correctly with the display and even has a shorthand way of creating the LCD for this case.
This board is for use with Arduino Uno and Mega devices, because they are compatible with the original wiring pin out spec. The pin connections are as follows:
When using with LiquidCrystalIO, you can use the no-argument constructor, which is specifically for DfRobot where the pins are known upfront.