Yes that software is on the site as well. It is written in the language called Processing so will run on any platform. It is all in the software bundle you can download.
Mike's page does say that he has software (written for Processing) that feeds the Arduino the Gcode.For other Arduino firmware that reads Gcode take a look at: http://www.reprap.org/wiki/FirmwareFor something comparable to Mike's Processing-based code try: http://replicat.org/
What sort of errors?I have used Inkscape with a Gcode plug in to convert text into Gcode for engraving. However it does produce some gcodes that are not implemented by a lot of rep rap controllers?If you look at the Processing section of my site I have some Gcode generators and viewers for PCB engraving.