The difficult part may be to get a CS/CS2. It can only be bought legally if it has not been used as the basis for an upgrade (to whichever version).
Have you tried getting ahold of Creo and asking them if there is an updated version of the plugin for PC? Then, it would just be a matter of an upgrade fee. If they do not have it, they may have an alternate vendor you could go to. That's where I would start...Creo. You might try Photoshop's Duotone capabilities where you can save Duotone sets and re-use them whenever. You could also create a script in PS to help with the automation.
@ john : I could try but apparently the company got bought out by Kodak and they no longer support it and haven't since CS2. And the problem with photoshop's duotone capabilities is that you have to first grayscale the image, thus losing all color data. So there is no way, for example if I am colorizing a purple car, to automate that, so I would have to go in and adjuts the settings until the red and blue ink are heavy on top of the car, which would result in a purple car when printed. For the amount of ads we do, this wouldn't really be feasible.
@ jacob : Good point.
Take a look at...
There are some PS Plug-Ins that may help you. Good luck.