I have been into my steering column (1991 300CE) more times than I can count trying to eliminate a flashing SRS light. Here are a few things:
The 10mm bolt has (blue) Loctite on it so it takes some effort to break the it free. As Mike mentioned, do not torque against the steering wheel lock.
Before pulling the steering wheel note the pencil mark on the steering wheel versus the mark on the splined column.
Hassman, maybe just a cleaning will solve your squeaking. Clean or replace the spring loaded horn contacts, cheap ($5). Clean or replace the horn slip ring ($80). Clean or replace the SRS contact ($35). Cheap part but you have to go deeper into the steering column and the lower dash has to come out.