Just follow these instructions (they're for the X1100 series, but they use the same driver, and this is how I got mine working). The important item is the secret '-keep' option, which unpacks the files into a directory. From there, you simply rpm2tgz them, install the ppd files in the correct location for cups to find them, and then tell cups about your printer. Once it's installed, you can use 'localhost:631' in your browser to adjust the printer's setup as you like.
http://www.linuxquestions.org/questi...t=lexmark+z600
And, I agree, what a pain in the butt. While it's nice they provide a driver at all, it would have been nice for them to document small, important items like this, or mention that the driver works for several different printer families.
Still, you can get it running, and it works fine, at least on 2.4 kernels (haven't tried it on a 2.6 kernel, was thinking about doing so this coming weekend if I have time).