I am working on replacing the Steering rack in my 98 SLS. Alldata says you must 1st lock the steering column before you remove the rack. It mentions a special tool that is inserted in the lower part of the steering column just in front of the steering wheel. Do I really need this special tool or can I just use a screwdriver or somthing?

Here's that Alldata says:

Steering Gear Removal and Installation

REMOVAL PROCEDURE



Tools Required
J 42640 Steering Column (http://www.alldatadiy.com/alldata/AFI~V6017414~C32320~R0~OD~N/0/56775861/62803304/62803317/62803318/34853741/34864218/34864219/34864220) Anti Rotation PinNotice: The wheels (http://www.alldatadiy.com/alldata/AFI~V6017414~C32320~R0~OD~N/0/56775861/62803304/62803317/62803318/34853741/34864218/34865428/34865429) of the vehicle must be straight ahead and the steering column (http://www.alldatadiy.com/alldata/AFI~V6017414~C32320~R0~OD~N/0/56775861/62803304/62803317/62803318/34853741/34864218/34864219/34864220) in the LOCK position before disconnecting the steering column or intermediate shaft (http://www.alldatadiy.com/alldata/AFI~V6017414~C32320~R0~OD~N/0/56775861/62803304/62803317/62803318/34853741/34864218/34864219/34864450) from the steering gear. Failure to do so will cause the coil assembly in the steering column to become uncentered which will cause damage to the coil assembly.

I've pulled several cradles and we never did anything special. We left the column with the key out.

If it has a non-locking column you should have the tool, a regular screwdriver won't work. The tool has a little bushing on it that holds it in place.
All you are trying to do is keep the steering wheel/column from spinning while you have it apart. If the column rotates during service when you reconnect it you might end up breaking the SIR coil, if it's not centered properly it won't turn far enough and the pressure from normal driving will overextend the coil and break it.
Those aren't really too cheap to replace either.
Just tie a rope from the wheel to the brake pedal or something so it won't rotate.