You can download the VM here.
Choose the Virtual Appliance under the 5.3.1 (current minor release as of this posting) heading - see screenshot below. If your cisco.com userid does not allow you to downlaod the image, please call the TAC and ask them to associate your ID with the product (you will need your sales order or support contract number).
Installation instructions and configuration guides can be found on the product support page here.
