Double Slips (unlike a crossover) are EASY to wire. The RED top rail lines marked are one potential - the BLUE bottom rail lines marked are the other potential. Only the frogs have to change polarity based on the points throw. One thing to note - the points on the right control the frog polarity on the left and vice versa. Think the points and opposing frog as a turnout.
Updated with clearer color graphic.
COSLAR RR - http://www.coslar.us/
NMRA Standards and Conformance Department
PROTO & FINE Scale Coordinator
I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.