RegCure will scan the registry regardless of the drive it is located on.
As you start windows, the registry is loaded into your computer's memory. The registry is where changes to your system and settings take place, and where information from programs you use is stored. This means you do not need to scan specific drives; the information in your registry is centralized and shared between all drives, hard disks, and partitions.
In the case of file information, RegCure will attempt to locate the file regardless of which drive it is on; if the file is no longer on your computer, RegCure will fix any associated registry errors.