I've posted a new version of a converter program that will convert WordPerfect files to the ODT format used by LibreOffice, OpenOffice.org, NeoOffice, etc.. These files can also be opened in TextEdit in OS X, though with less-accurate formatting.
This new version can convert password-protected WPMac files if - and only if - you know the password. It's based on the latest version of the libwpd conversion software largely written by our Fridrich Strba. The new version was posted yesterday, and I've managed (mostly by dumb luck, not skill) to build a version for OS X.
Download link here: