I'm hardly an expert on these guys, but are you absolutely sure they're responsible for the damage? Or are you just assuming because they're the only crawlie things you're seeing, they must be causing the damage? Only asking because I've never, ever seen even the slightest bit of evidence that the average pill bug is anything but a detritivore.
That being said, I haven't had much luck with diatomaceous earth in general, but certainly not against pill bugs. About a decade ago, I had a real problem with them after summering my plants outside for the summer. At the time, I worked with an expert on insecticides, who told me that there aren't really any good, effective, and long term remedies for pill bugs ... just get used to them.
In my experience, the best way of minimizing the population is to individually submerse pots in a bucket or sink. Then you can pour off the individuals that crawl out of the mix. For me, the smaller ones are fed to my fish, who seem okay with that arrangement.