I would like to know how to call the CD-Rom, or rather search for its drive letter.
You can use the FileSystemObject (Microsoft Scripting Runtime in the references dialog). Iterate through the Drives collection of the FileSystemObject and check its DriveType property and DriveLetter property. DriveType 4 is the CD ROM.
Set a reference to the Microsoft Scripting Runtime and try this code.
Dim objFso As New FileSystemObject
Dim objDrive As Drive
For Each objDrive In objFso.Drives
If .DriveType = CDRom Then
MsgBox "CD ROM is " & .DriveLetter