How can you override the storage policy and provision a VM to a different datastore?

Problem:

I need to be able to provision a VM to a datastore that is selected by the user, preferably via a drop-down menu. Currently the HDD is being created in a temp datastore and later being moved to the proper location but I am hoping to just be able to provision the VM to the proper datastore initially. What makes this difficult is the "proper datastore" is VM specific so I cannot just set it in the storage policy. Any assistance would be greatly appreciated.

Solution:

there is a check box the the user to select the DS.

or you could use categories for the VDC