Security system shut car down

Usually there is the lock cylinder and ignition switch, two different components.
I'd imagine, removing the steering column is just nuts and bolts, plus wiring connectors.
Are you going to reuse steering column or replace it?
If new column, you may probably need a new lock cylinder, a new key usually comes with lock cylinder. Then I'd be concerned about your security system, where applicable. If vats security system there is info all over the internet bypassing the pellet in the key.

Mostly the security system cannot be by-passed. It would not be much of a security system if it was easily possible. With some variations a code is recognised when the transponder in the key is in close proximity to an antenna which is in or around the steering or ignition lock and the antenna signal is sent to a black box.
When the code is recognised by the black box or ECU it generates and sends another code to the engine management ECU instructing it to switch on and the engine will then start.

Obtaining and fitting the new steering lock and keys and having the system recoded is likely to be expensive and inconvenient - it is designed that way to discourage vehicle theft and is why these days most car thefts are as a result of successfully stealing keys.

If the car is of low value it is possible to have the engine ECU decoded so it will recognise any code so the engine will start and run. In the UK the procedure is done mail order and takes about a week and costs around £100.

The problem is with the factory security system; you'll need to reset the security code matching between the security system and the code on your keys that came with the new column.

the key has a small sensor that recognizes the car so the key must match the security system... when changing the steering column with new key you must change security box from passenger side kick panel..

you need to get a new ign. lock cylinder and chip key. Or you can get a lock cylinder and copy your old key with a regular key no chip. Take new cylinder, put old chip key in it. Plug into harness at the bottom of steering column just behind the dash, fine orange wire from existing one in the column. Hide lock cylinder under dash and start car with copy of old key.

The ignition key cylinder in a Buick unlocks the ignition and allows the Buick's engine to start. The cylinder contains a switch on the end of it (inside the cylinder) that sends an electric signal to the starter motor. When the ignition key cylinder fails, the Buick won't start. When this happens, you'll need a new ignition cylinder. Purchase replacement cylinders from Buick.
Difficulty: Moderately Easy
Things You'll Need:

• Ignition key
• Punch pin
• Cross-point screwdriver

1. 1 Remove the screws on the bottom of the steering column on your Buick. These screws hold the steering column cover on. You may need to tilt the steering wheel to its highest position to access these screws.
   
2. 2 Turn the ignition key to the "II" position in the ignition cylinder.
   
3. 3 Slide the punch pin into the access slot on the bottom of the ignition cylinder.
   
4. 4 Push the pin all the way into the access slot while you pull the ignition cylinder out of the steering column.
   
5. 5 Insert the new ignition cylinder into the steering column with the key in the "II" position on the cylinder.
   
6. 6 Push the cylinder into the column until it "clicks," indicating that it is locked into the column.
   
7. 7 Turn the ignition key to the "Off" position.
   

turn it in to your insurance, you are most likely going to need an entire new steering column to fix this.

Turn key on for 10 mins. security light should flash for ten min. go off turn ignition off and back on repeat procedure 2 more times total of 30 mins should crank up

Replace the ign. lock cylinder. Put old chip key in new cylinder. Plug it in to the connector at bottom of steering column by the dash after removing the wire from old lock cylinder. With duplicate key to turn old cylinder start car. Be sure to clean the battery cables and replace bolts. Hide the new cylinder under dash with chip key in it.

You have to use the lock cylinder and key from the original column, the keys have a small piece or resistive wire that the sensor in the column reads and if the wrong resistance value is read then the starter or fuel pump are locked out, your car came with a factory security system so don't know why another was added, but the reason above is the problem.