Have you tried using the VBScripting object? Add a reference in your Project to "Microsoft Scripting Runtime".

Try using this Code:
Dim FileSys As FileSystemObject
Dim iDrive As Drive

'Open a New Instance of the File System Object
Set FileSys = New FileSystemObject

'Iterate through the Dives in the File System
For Each iDrive In FileSys.Drives
If (iDrive.DriveType = CDRom) Then
'Do what you want here
End If
Next