No need to remove the steering column from the car, if it's like other GM cars of that era. In reality, you don't even need to "drop" it.
If it's like other similar GM steering locking steering columns, what the key goes into is only the ignition lock cylinder. There is a gear on the end of the cylinder that moves a "rack" which runs a rod that works the actual electrical switch at the base of the steering column. Just two screws hold the switch to the top of the column's "jacket", usually a long rectangular switch with the ignition wiring harness plugging into it. Probably plastic now, but the original one might be more of a ceramic construction.
With the key in "LOCK" position, when you get the switch off of the column, the new switch should have an "index pin" in it to hold the inner slide in a particular position for installation. With the trans in "PARK" and the ignition in "LOCK", the new switch should go on where the earlier one was with little change of the ending position. Remove the index pin before use, but after installation. Probably about a 30 minute job.
The ignition switch will run "parallel" with the column. The backup light/neutral safety switch runs "across" the base of the column, parallel with the firewall.
Even if the reason the switch is not working correctly is wear on gears and rack, the disassembly to fix that (with a new rack "kit", or pieces thereof), can be done "in car" too.
Just run the seat all the way rearward and ease into the floorboard and you'll see where everything is located on the lower part of the steering column.
Enjoy!
NTX5467