Setting Static Drive Letters in Windows 8

Using Parallels 9.0.24251 on Windows 8, I have a USB-connected storage drive and its drive letter bounces around all over the place. One bootup it's assigned U:, the next bootup it's assigned Z:
I found this article describing how to set up static drive letters in Windows 7 but cannot find a similar thread for Windows 8. Here's what I'm doing:

• I have verified that the drive is accessible in Mac and Windows.
• I go to Control Panel\System and Security\Administrative Tools and select Computer Management.
• I then select Disk Management. Unfortunately, my external drive does not show up there. This is where I think the drive letter can be manually assigned.

Again, the drive is fully accessible from both Windows and Mac. Any suggestions?