Kel,
You will need a design software like Adobe Illustrator/ CorelDraw/ Flexisign/ Signlab etc etc for your designs and then to output for printing use the Roland colourchoice printer driver for the PC-600 available from Roland japan site i believe. The driver will only work up to Windows XP.
You will also need a serial or parallel lead to link the machine to the PC or if you haven’t got a dedicated serial or parallel port on your PC then a good USB to parallel lead. I use a Belkin one with no problems, don’t go for cheap alternatives as they won’t work.
Alex.