Please note this software is more of a utility than an app; also, its primary function is to mount existing virtual drives. It can create one, but depending the settings you choose, it typically sets up a temporary drive that only lives in memory - either physical memory (RAM) or virtual memory (pagefile.sys).
My solution was to create a VHD the normal Windows way (Disk Management utility), leave it empty (i.e. don't put your maps in there yet), mount it with ImDisk being sure to check the "Removable media" box (see screenshot below), and then copy the maps into the virtual drive after it's mounted.