I would try to discuss w/your ped ahead of time and have a plan with them to cover all of the 'what ifs'. Otherwise, I would think that just repeating no, no, no and never letting baby leave your side would take care of it. Also get everyone with you (DH, your parents and ILs). If baby's latch is ok, baby will be getting colustrum- just not milk and that should be enough.
If you really feel you do not need the supplement, just say no. They work for you and you don't have to do anything you don't want to. (I would think they would need a court order to go against your wishes, but I'm not a lawyer and have no idea for sure.) If you decide a supplement is necessary, definitely go with any of the alternate feeding methods and not the bottle.
Print out all of your resources and bring them with- or bring any of the books you've used that will show supplementing isn't necessary. You can have printed back up that way. Even discuss it with your ob. They may not have much to do with it, but the more people you have on your side, the better.
Check ahead of time to see if the lc on call is IBCLC and if not, what experience she has. This may make you more comfortable taking her advice if she does recommend a supplement.