When we did this two weeks ago at VGF, we asked our guide so that he could add our name to the security gate when we drove in. Although I'll add that when we arrived we simply told security we had an appointment to tour the
DVC villas and they just let us on in. From there we walked over to Poly and did the tour there without setting up any appointment and they showed us a studio and a bungalow. If you're at the resort you can pretty much just go up to the DVC booth and say you want to tour the model rooms, no appointment needed.