the crossovers my fronts came with you just run the 1 channel out of the amp into the crossover.. then the crossover has 2 outputs, one for the tweeters one for the woofer.. makes life easy.. i would think your alpines would have that too..

i dont have them with me but iirc the stock tweeters to have a crossover in the wiring attached to the tweeter so if you splice in your own wiring you wont be using it