There are plenty of wiring digram's online if you look.
Thke a look at the manufactures of marine battery switch's.
http://www.jerrylabella.com/ship_shape2.htm
http://www.cmsquick.com/tech_03_batsel.html
I'm using 2 of the Newmar Battery Integrator's. This will be setup with 2 outboards and 4 batteries. 2 dedicated starting batteries and 2 House batteries in parell.