I've done a test layout to play with that I'll be testing in the next few days. Below is the layout.
Several folks have asked about using Arduinio hardware with APRS TNC. I don't have a lot of motivation but figured I'd get the project started. If you have an arduinio and would like to help develop this using arduino hardware please post (no emails please). Here is the alpha schematic I'm working on using the display I started with in the original design.