In the install4j Launcher, I’d like to run a small snippet of custom code (like the Run Script Action) in order to set a CLASSPATH directory conditionally on a number of things (OS, the user launching the application, whether the directory exists), and add that directory to the Class path in the Java invocation of the Launcher.

Specifically, can I set a preferred class path for a Launcher’s Java invocation to a folder in user-space, which will depend on the OS and the installation instance (probably something like
%LOCALAPPDATA%MyApplicationProfileshexcodeforthisinstallation on Windows;
~/Library/Application Support/MyApplication/Profiles/hexcodeforthisinstallation on macOS;
~/.local/share/MyApplication/profiles/hexcodeforthisinstallation on everything else)?

This is for a multi-user environment so the installation user can’t be used.