Are you talking about a four of six-cylinder engine? The six-cylinder is not adjustable. The EZL module controls timing using the TDC sensor on the front balancer and manifold vacuum as inputs.
My erstwhile '84 four cylinder 190E had a conventional electronic distributor, and the timing could be changed by rotating it, but I don't know if the later four-cylinders had this setup or a system similar to the sixes.
The distributor at the front of the head on a six just distributes the secondary voltage. It cannot be used to change the timing.
In the last six months there have been discussions of changing the timing by changing a resistor. You'll have to search for it. Changing the resistor apparently changes the rate that timing is changed, but not initial timing and is used to "tune" the timing map to different fuel octane ratings.