If you had a Mac, with MAMP installed, it would be as simple as going to the Dashboard, clicking the little "i" for info on the MAMP dashboard widget, selecting PHP 4, then clicking "Done". Depending on your setup (if you configured it to use the default Apache port 80) you’ll be asked for your user password so the Apache server can be restarted.
Having done that, and corrected the error on line 77, I find this in my browser’s error console:
Error: $("interaction") is null
Source File: http://localhost/5615/assets/modules/docmanager/js/docmanager.js
Line: 123
I also get this one:
Error: top.mainMenu.stopWork is not a function
Source File: http://localhost/5615/manager/
Line: 1
Switching back to PHP 5 now.