See e.g. here:
The basic idea: create an action of the type "Format value" for directory and set an absolute path with text constants like "d:\mymusic" and variable like %label%, e.g. "`d:\mymusic%label%"
See e.g. here:
The basic idea: create an action of the type "Format value" for directory and set an absolute path with text constants like "d:\mymusic" and variable like %label%, e.g. "`d:\mymusic%label%"