I do not have the fridge you have, but I was also worried about making a random hole on the side of the fridge. Mine is an older fridge as well and actually had a little strip of metal that holds the shelf’s up screwed on the side of the fridge. This strip of metal, has holes in it that you insert the shelf’s into. Anyways this strip was screwed onto the side of the shelf using 3 screws, I figured if they screwed these screws into the side of the fridge then there must not be any danger of hitting a wire at that location. Basically I took of the strip off and used the holes where the screw used to be to drill the CO2 line hose.
Worked like a charm! Hopefully you have something similar.
I found a diagram of your model fridge and you should be golden. If the following picture justifies your situation then it is exactly like mine.