Is it possible to load and unload unpacked Chrome extensions from the Command Line?
Yes, although only temporarily *:
chromium --load-extension=path/to/extension
If you want to load multiple extensions, just separate the path by a comma:
chromium --load-extension=path/to/extension,path/to/another/extension
Replace chromium
with chrome.exe
(or whatever is used to start your Chrome/Chromium browser).
* When you close the browser, and starts it again without the command line argument, then the extension will disappear from the list of installed extensions.