She won't need that if you work her up gently, starting with your oiled up finger for a few minutes first...some tongue action on her pussy at the same time is always nice. Just go slowly and make sure your cock is really slippery before you slide it in.
good call. as long as you're slow and gentle in your approach she should be just fine. the first time i had something in my a-hole was weird, but the doctor was slow and gentle when he massaged the rod into the stink-chute. that scope was easily bigger than most pricks i've seen on TV, but i took it pretty well for an anal virgin