Unfortunately, the upcoming preview release will not be able to work at all with external programs like Dr. Eye and PenPower, and I'm not sure if there'll ever be a version that supports Dr. Eye.
In order to stop having to produce massive updates with every new Palm OS release and fix some long-standing problems with Chinese text display, we've written a text display system for PlecoDict that's almost completely independent of Palm OS - this provides a lot of benefits, but one of the downsides is that programs like Dr. Eye have no easy way of figuring out what text is located where on the screen because they don't know how we store or encode it. We haven't actually tested our software with Dr. Eye yet, and if it has the option of pulling text from the clipboard then it might work with the final version of PlecoDict, but I'm afraid it's pretty unlikely. PenPower should work in the final version because we'll be adding an interface for you to input characters from external software like PenPower, CJKOS, HanWang, et al. Unfortunately, though, that feature isn't available in the preview release.
But out of curiosity, why are you interested in using these two pieces of software with PlecoDict? Our own built-in handwriting recognizer now allows you to write characters right on the screen, so there's little advantage to using PenPower instead, and our software also includes the ability to quickly look up a word in a dictionary entry - you simply highlight the word and tap on a button to bring up its definition. In fact the old Oxford Dict software and the finished version of PlecoDict both include the ability to do what Dr. Eye does and look up words in other applications. And actually Wenlin on PC has that ability too - simply holding your cursor over a word in Wenlin will bring up its definition on the bottom of the screen.