Just completed the installation of a new ignition switch for my 88 560SEL. I followed the advise of andmoon but thought I'd add a couple of helpful hints:

1) Extend telescoping steeing to max out.
2) Place front seat in most rearward position.
3) Disconnect battery negative cable.
4) remove instrument cluster
5) turn key to #1 postion and remove plug in back of switch (turning key is required to "unlock" plug from switch).
6) Feel around (can't see due to angle) for allen bolt on top of ignition cylinder that mates with steering column and loosen (no need to remove)
7) remove two bolts (13mm) on top of steering column allowing column to drop about 3".
8) look for "release button" that resides on the steering column where ignition cylinder enters column. You'll see (need strong light) this release button as you look in-between the column and the 180 degree plastic trim piece that is attached to dash.
9) turn key to position #1 and push release button with a heavy wire while pulling ignition cylinder to right.
10) remove key to allow ignition cylinder to continue to the right.
11) orchestrate the complete assemply out through the instrument cluster opening.
12) you can proceed to remove old switch from ignition assembly with all accessory wiring to ignition cylinder remaining in place.

The new ignition switch does not have an enlarged white plastic "wing" that is in the original which required the key to be in position #1 for the plug to be removed.

Others are correct that in using this procedure, one does not need to remove the steering wheel nor the lower kick panel.

No I'll wait and see if this was the cause of my occassional stall/stumble. Fingers crossed!

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Woody