As long as you provide the owner with your trip information they can make the reservation for you. The only inconvenience is that you cannot make the reservation, it has to be done for you.
I am not sure if I happened to get a DME rep who didn't know the system, but I rented points before (through a 3rd-party service) and was told I could not make DME reservations by the service and have seen it on the boards. Since it was getting close to my departure and I hadn't received my luggage cards, I called DME myself just to check on the reservation. The rep told me he did not see it (I won't get into that on this thread) but that he would be happy to add it. I told him I was NOT a DVC member and that I had no member number. He told me that wasn't a problem and that the reservation was in my name and I had the reservation number so he happily added my info and quickly sent out my packet (less than 2 weeks before I was leaving!). This just happened in December 2011, so not very long ago.
To be sure, my understanding is that DME is NOT run by Disney (or DVC or any part of Disney Vacation Development), but by MEARS. Although this may not be the way it is _supposed_ to be handled, in the future I will always check for myself about a month before my departure so I am not stressed out about my luggage again.
YMMV.
Ii have rented points for next month and booked DME recently, and all I needed was my resort confirmation number. Don't mention DVC, and you will have no problems booking.