Small Engines (Lawn Mowers, etc.): lawnmower, electric starter, electronic ignition

Question
I NEED TO KNOW WHERE EVERY WIRE GOES.IM IM CHANGING A PULL START TO AN ELEC START.IT HAS AN EXIST. KEY THAT SHUTS IT OFF.I WANT TO USE A PUSH BUTTON TO CRANK.NEED TO KNOW WHERE ALL WIRES GO.ALT,POS.WIRE TO SOL.,EACH WIRE FROM PUSH BUTTON,DO I NEED TO GROUND SOL.?OR IS THERE AN EASIER WAY?  

Answer
Hi Ross
First things first.  Do we have a mower here that is able to be configured with an electric starter?
DOes it have points or electronic ignition?
Does it have a altenator circuit to re-charge a battery?

Reason I ask is sometimes its easier to install a modification to allow use of a 110vac starter, and in some cases an adaptor to allow use of a 1/2" drill.

Reply to this and lemme know what kind of mower it is, make of engine, about how old and we can go from there ok?