MacPCLtoPDF (inspired by GhostPCLx) is an AppleScript application bundle that converts PCL and PXL files (and Windows PRN print files in PCL format) into PDF format. It is merely an AppleScript wrapper around a compiled copy of GhostPCL (which is released by Artifex under the GNU General Public License). GhostPCLx doesn't work on OS X 10.7 or later, so I prepared this to take its place.
See the developer's website for instructions to make the AppleScript open the PDF automatically in Preview. Add A4 to the application name to force A4-size output.