VMTOOLS needs to be installed for the Paravirtual Driver to be available.

So...

 Use SAS driver, Install OS

Once OS is installed

Add additional small drive. (say 4 MEG), Selecting SCSI  1:x, or 2:x, this will add a new controller.

Change that controller to Paravirtual.

Format the new drive.

Once done, 

Shut down VM.

Delete Small drive.

Change SCSI controller for original disk to Paravurtual

Power on vm.

Should be good to go.