Well, Storage Profiles do the trick. Even if your storage array has no built-in storage capabilities, you can define your own capabilities, add capabilties to all datastores of a type, and assign capabilities to a storage profile. You can then add datastores/datastore clusters based on a profile to the provider vdc.
Of course it requires Storage Profiles and the right edition of vSphere.
Thats only a short secription how to do it, but the vmware documentation is quite good about it