Windows 7: Assign Cardreader drive to folders

I have USB internal cardreader (iTec) which has four slots and in system shows 4 letters of drives ussually. In windows XP I used to remove this letter assigning and let them assign to 4 different folders (XD,SD,CF and MS) - because of toooo many letters in my computer.

Now I tried the same in Windows 7 Pro x64 but after restart was appeared in four yelow mark exclamation with Portable devices in device manager. When I reassign back to letter and remove assigning for folders - device manager is OK

There is also new feature "Hide of empty drives" but it does not work with Total commander



Is this Windows 7 bug? Exist some way how to assign empty cardreader drives to folders, not to letters?