When I try it, it just installs the user launcher_profiles.json file and the Minecraft game folders directly into the 'Users/Username/AppData/Roaming' folder even though I have a. I couldn't get a junction (symbolic link) to the '.minecraft' folder to my old drive to work with MinecraftLauncer.exe (for me anyway). Oh, BTW, my '.minecraft' folder is over 11 GB in size so moving it onto my SSD is not desirable. It is the rare user that even knows to back-up the Users/AppData folder. It is frustrating that so many programs are installing onto the OS drive and using the 'Users/Username/AppData' folder without the option to select the location I want it in. I don't want my new SSD filling up with data which can easily be accessed through another drive. I had to install a new SSD for my operating system (Windows 10) and needed to access all my AppData on my old drive.

I, too, wanted to use my '.minecraft' folder which was already installed on another drive. There was no solution for the current launcher (version, Sept 12/2018). On an old thread, the question was asked how to move the '.minecraft' folder to a different drive.

Move appdata to another drive