What are you trying to achieve? Currently, CPU throttling only limits the number of CPUs that QV will consumer on a particular machine. It is pretty straightforward in terms of setting up so I assume that you are seeking to do something else?
Throttling will in almost all cases will hurt performance in a mulit-user deployments. You already have a penalty (overhead) with running QV in a virtualized server - your best bet would be NOT to throttle and to ensure that your virutal machine has dedicated CPUs/RAM and is not sharing its CPUs/RAM with the other images on the physical machine.