Command prompt and VM settings

Hi

Using the command prompt in Windows 7 64-bit, how do I set up an ISO image in the CD/DVD setting of a VM created with Workstation 9.x? If it is possible to do this, how do I delete that ISO, and set up a CD/DVD standard device assigning a letter specific to this virtual device?

In addition, again using the command prompt, how do I change the operating system setting of a VM?

Thanks

Bye