Before we start, a short word about prototyping the crossover. A crossover is a hard thing to prototype because you need very low impedance connections. Lots of alligator clips are not a good thing. I've ended up using special connectors that screw down. I solder the base of the connector and use the screw-downs to get low impedance (but easy to change connections). Here's a closeup of the technique.

My first proto crossover looks like this

There are a couple of alligator clips, but they connect unimportant things (for the most part). if you look closely you can see the connector blocks connecting the components together.