Unfortunately, there are some significant limitations with the built-in 'subst' command under Windows Vista and above.

It is just one more Windows feature added for backward compatibility with old programs and batch scripts. Generally, a virtual drive is a symbolic link in the local MS-DOS device namespace. Visual Subst provides you with a clean, simple and distraction-free user interface where you can manage all your virtual drives at any time. You can use virtual drives everywhere – it's so much easier to access files in a project directory you are currently working on using just a single drive letter. Also, Visual Subst makes it easier to create, edit and remove virtual drives in a GUI way. It solves 3 main issues with the built-in 'subst' command: it seamlessly creates drives for elevated applications, adds editable drive labels and restores virtual drives after reboots. Visual Subst is a handy utility which allows you to associate the most accessed directories with virtual drives.

Download Visual Subst 5.4