With Alcohol 120% open, go to File>Options>Virtual Drive
There you can choose how many virtual drives you want to use.
Now if you have the disk image on your hard drive just go back to the main screen and right click the virtual drive and mount the image onto it.If you don't have the image saved this is what you do....
Go to this site and find out the type of copy protection the disk has.
Once you find out the copy protection put the disk in the drive. After that run the Image Making wizard.