@WillersU thanks for the comments.

Adding the ISO to the CD either in settings or the Virtual machine menu will work. You do have to make sure the virtual CD is set to connect to the VM if you do it through settings before booting the VM. I’ve forgotten that one a few times.  

The idea to use the updated Leap image is a good one.. I’ll make a note of that in the next revision to the guide (coming soon!).