I also have had the same problem with Maxwell Render MacOSX 1.1.33 alpha. I followed all the steps and the application just bounces a few times in the dock and then nothing. Starting from the terminal I get an error message..."illegal instruction". I tried repairing permissions, checked the installation, the license file, the environment.plist file all to no avail.
I had no problems getting the previous release to run from the command line. I'm also on a Dual G4 if that makes a difference.