Custom Scan - is it more customizable?

I only see the following folders in the Custom Scan section:

Common_Appdata

Common_DesktopDirectory

Common_Documents

Common_Programs

Common_Startup

Program_Files

Program_Files_Common

System

System_Drive

User_Profile

Windows

Is it possible to be more selective with these custom scan?  What if just want to exclude one of these folders?  Or just scan a single drive letter?

Thanks,

Brett