I am now a member (yay!) but I have rented before as well. And I, too, wanted that confirmation...just as a measure of comfort. After all, you are giving a sizeable chunk of change to a stranger and hoping that person will behave in an honest manner. I understand where you are coming from.
However, here is where/why you will not receive much sympathy from those on this board:
As members, we pay relatively hight maint. fees (dues). One of the things these dues cover is the cost of Member Services. Our dues pay for their salaries, offices, overhead, etc. Thus, many members feel that the MS CMs' time should be spent servicing members...and members only.
If you truly need confirmation and need it quickly you can get it by doing the following: Contact the member from whom you rented points. Ask that member to contact MS and have MS fax them the confirmation. MS will usually do this the same day (at least this is what I have been told...never actually done it). Then, once the member has received the fax, he/she can fax it on over to you the same day.
However, all of this is somewhat unnecessary unless your trip is this week. Once the member makes a res in your name (and it will have your address on it, etc.) you will receive written confirmation from Disney...an actual letter with a reservation number on it and everything. Assuming your trip is at least 2 months away (and it is likely more), you will get your confirmation way before your trip. Thus, I would just wait and skip the whole faxing thing.
Also, what others have said here is accurate...even though you get that paper from Disney with your name and confirmation number on it, there is nothing to keep the member from whom you rented from calling Disney and simply cancelling the reservation. Disney would not contact you to tell you that the res. has been cancelled since you are not the member. Please note that I am not saying this to scare your nor discourage you from the transaction. I think that the vast majority of
DVC rental transactions go off without a hitch, so you are likely all set.
If you are truly nervous about the whole rental transaction, you can use one of the many sample contracts that are available here on the DIS.
I hope that your rental goes smoothly and that you fall in love with whichever DVC resort you rent.