You have to place in DVD 1 for X1 and when you get to the choices to select the items to install, deselect everything and then ONLY select Guitar Rig 4 LE. You will be promted for the Original Sonar X1 Serial and Registration Key, BUT WAIT!!!!! This will cause problem when you restart Sonar.
NOW hold on, because I did this the other day and my Sonar Expanded was hosed. IF you updated to Sonar Expanded or any other Version that gives you a newer serial and registration code, then your Sonar will revert back to the original Sonar X1 and not work because it is the Expanded version but it has the original X1 serial in it now.
I had to send an email to Tech support for them to tell me how to fix the problem with a registry hack. I got my email back today and I am going to apply the hack to see if I can get my Sonar working again.
Peace