Crossovers

Me and my dad recently put some Infinity Kappa 5.25 speakers in my 96 cutlass supreme and we also put some kicker R19 tweeters in. The tweeters have passive crossovers but the Kappas dont. They are going to be hooked up to the same 2-channel amp. To hear the speakers we hooked them up to the radio and the kappas were getting to much bass. The tweeters sounded good because of their crossovers. When I hook the amp up I am going to have the onboard cossovers turned off so they wont interfere with the passive crossovers. This will cause the kappas to run full range and get too much bass. How will I be able to get the kappas their right frequencies. Because using the amps crossover will interfere with the tweeters crossovers right. Please help!