Being the first release under MacOSX we have simply adapted our UNIX shell installer. Most those requesting seemed to be familiar with the UNIX side of OSX but for those that are not, here are a few steps to get things going.

Put the installer on your desktop.
Open a terminal (Applications->Utilities->Terminal)
Change to the Desktop in the terminal (type: 'cd ~/Desktop' then enter)
Ensure the executable is executable (type: 'chmod +x picc-demo.run' then enter)
Run the installer (type: './picc-demo.run' then enter)
Follow the prompts to complete the installation being sure to enter full path names when prompted. eg. /Applications/HI-TECH/PICC_9.50 or /Users/username/HI-TECH/PICC_9.50
*To configure the environment variables you simply have to logout & login (of OSX not just the shell).
HI-TIDE, if installed, is an app package which can be moved around and double clicked from a finder window.
HI-TIDE requires JAVA 1.5+ this can be downloaded from: http://www.apple.com/macosx/features/java/

* if you already have a ~/.MacOSX/environment.plist file the installer assumes you know what you're doing and you need to add the entries manually as prompted.