With the old launcher I was able to create a "portable" version of Minecraft in 2 ways.

jar version of Launcher: java parameter -Duser.home
"native" windows version: set environment variable APPDATA

In both ways all the configuration and game versions where installed to the specified directory.

The new launcher ignores the environment variable at all and always uses C:\Users\XXX\AppData\Roaming\.minecraft

There is no way i can carry my minecraft usb stick arround and play where I want without having to install anything anymore.