it tells you to do those things because "to make it easy" the exhaust should be lowered out of the way.
the horn and radiator are a part of the process to get to the exhaust flange bolts.
as for replacing the "o-rings" goes...they are really copper crush gaskets that are "intended" for one time use. if you are carefull or they were not damaged during the factory install...you might get away with using them again. if not...you'll have an exhaust leak near the motor that could sound like a loud ticking...
they are just following the manufacturer's guidelines for the procedures.
chances are good that if you bought the clymers, and thought enough of it to ask....then just ask around for some of the guys in your area if they have the time to give you a hand...this is a low ~ moderate skill level task that shouldn't require too much effort.
it will however provide you with exposure to several parts and knowledge that some Busa owners never get...so take advantage of it.
glad you came forward before hand rather than after the fact.