You could try Eldragon. He DIY'd a pair of Wilson's a couple of years back...
DIY WATT crossover network?
I just fried the tweeter part of a crossover in my WATT/Puppy 5.1s (freak accident--don't ask... ;) and need to replace it. A very well-respected amplifier designer whispered in my ear that I might be able to DIY a better one, rather than buying a replacement. Has anyone out there tried such a thing? (I have a good Pace iron & can solder well, but can't begin to design a crossover network myself).