How do you install crash bars on a Honda 500 cbf 2007?

There are various kinds of crash bars available for this bike but they all have in common that they are bolted onto the engine crankcase and the bike frame. It is not possible to answer your question unless knowing exactly what kind of crash bars you are going to use. Get a set of crash bars, fit them into their approximate place and you will see which bolts to unfasten on the engine to fit the bars against the bike. In a few cases extra fasteners may have to be welded against the bike frame. This all depends on the kind of crash bars you have or intend to get.