Just put a zero in the rewards box and it will accept your entry. I looked at the rules and it does not say you have to have the Harrahs rewards. I think that is agains the law to require that anyway. They may want to see how many of their Harrahs card holders are applying as they can get discounts another way usually.
I will say their $60 price for Nevada locals tickets are not all that great. I called today and they are like off to the side and in that theatre if you like musicals you do not want to sit that far over. Plus it was up 7 flights of stairs. I told them I was handicapped and they said an usher would help me. The box office needs a lesson in how hard it is for a handicapped person to walk up seven flights of stairs. I know they have handicap further down, but those are for the rich handicapped people I guess. Sorry I am a little upset with them about getting one ticket to see a shwo I was going to review for them. So I will just not see the show, no biggie to me. :)