Actually, you can just be a listed Guest on the reservation. You'll have to be prepared to show it at the front desk if asked for it. But I think if you want the reservation to be in someone else's name, you'll have to book it over the phone (or through a travel agent). I don't know if you can do that online.
Also, the rule is one room per AP discount. So if you have two rooms, you'll need two people with APs to get the discount, though you don't have to have one staying in each room. (Example: A few years back I went with 3 friends, we stayed at Riverside in two rooms. Two of us had APs, two did not. Even though the two AP holders stayed in the same room, as long as two rooms = two AP holders, all was fine with the front desk)
-Rob