resizing spokes

I just bought a shift kit from Sick Bike Parts and I plan to use it with a Nexus 7 speed but I will need different length spokes. Is there a way to re-size the spokes without a machine? The bike that the seven speed is coming off of has the right size spokes already but they aren't nearly as heavy duty as the ones on my MB right now.

There's no way to do it without a spoke threading machine, and those run well over a thousand bucks. You're probably going to have to buy new spokes. Take your rim and hub into a bike shop and have them sell you the right ones.
The Nexus hubs are great, I've used several and have always been pleased.
Cheers, Geoff