I'm not renting points. I'm using my own. But I was able to enter my DVC reservation numbesr into MyDisneyExperience without a problem. I expect that anyone who has their reservation confirmation number could do the same thing whether they are an owner or a "guest" of the owner.
I could link tickets to that reservation if I wanted to and there is a link for the FastPass+ feature. The link is unusable since my resorts are not participating in the testing. However, it is there and I imagine that whenever Disney goes live with the whole Magic+ thing, DVC members and their guests will also be able to access FP+