Minify ships with "Builder", a simple Javascript app for constructing URIs to use with Minify. (screenshots of the 2.1.0 version)
It also does some run-time checks of your PHP and Minify configuration to look for problematic settings like auto-encoding.
After installation, this is found at http://example.com/min/builder/
You must enable it by editing config.php and setting $min_enableBuilder = true;
After use, you should disable it by resetting $min_enableBuilder = false;