Hi Bill, the wiring diagrams for the 4/4 to 2004 show that blue/yellow and red wires in the dash loom are already there to benefit front fogs but could be used equally well to power spot lights. They are probably tucked out of the way behind dash and just a simple single pole switch is required between the two. The blue/yellow switched wire then feeds to the main front chassis loom via multiway connector and splits to feed left and right auxiliary lights. Typically you should find wires of those colours tucked away on the inside of each wing. Removing wheels and rinsing crud off should reveal.
As Jon suggests though it depends how you want these auxiliary lights to be controlled. The red wire mentioned above is live with side/headlights but typically spots would be controlled by main beam selection. Either way extra current will flow through main light switch contacts so better to use a relay with just its coil energised by your additional spotlight switch via high beam (blue/white wire). Providing an additional dedicated fused battery supply to main contacts on relay would then allow switched power which when interfaced with the existing blue/yellow wire behind dash will power spots.
Relevant GoMog wiring diagrams
here
