Reason being, it'* not just a steering wheel puller you will need, but another special tool to get past the air bag and to the switch itself.
I had mine apart ('93 SSEi) a long time back for a similar repair, and I've been racking my brain just now to try and remember what that second special tool was (other than the steering wheel puller), and just realized that it'* the Lock Plate Compressor.
Removing the lock plate (part of the assembly that locks your steering wheel when you take the key out) is what gives you access to the ignition switch, turn-signal assembly, VATS wiring to the ignition lock cylinder, and other miscellaneous stuff in there. This is not really related to the air bag; that item you'll have unplugged and removed back around Step 3 of the whole process.
The plate compressor is what enables you to press the lock plate down far enough to reveal its retainer clip on the steering shaft. You crank it down, then go at the ends of the retainer clip with a couple of pointy little tools of your choice, until you're able to pry the ends of the clip out of its groove in the steering shaft, and pull it up and off. At that point you can remove the tool and lift off the lock plate.
The lock plate compressor is not expensive and fits all kinds of cars. You should be able to find one at most any parts store -- come to think of it, you might be able to rent/borrow one for free from Auto Zone -- and I can't imagine replacing the entire steering column as an alternative, to be honest, since if you've got a wheel puller, a lock plate compressor and a service manual, you have pretty much all the specialty stuff you need to disassemble the entire steering column. Once you've opened it up, replacing the turn-signal switch isn't too horrendous a task.
(Sorry, I don't get in here much anymore, but I hope this helps)