Take a look at the model.cfg and search for the steering wheel animation:
This is what you're looking for, but keep in mind that this value will be be multiplied by Axle_Steering_0_L.
So in order to sync the 3D steering wheel to 2200 degrees (1100 degrees in each direction), you'll first need to know the max value for Axle_Steering_0_L (e.g. turn the wheel "hard over", save the situation and check the laststn.osn for the exact value). Let's say, it's 0.7 ==> 1100 / 0.7 = 1571 is the value needed for the model.cfg to give you 1100 degrees in each direction.
You will notice that even after syncing, the steering curve in OMSI isn't 100% linear. This tutorial might help for the last bit of perfection: LINK
Please note: This is the usual approach on "normal" buses without fancy config files in the background. Other buses like the MAN NLC or the Thüringer Wald buses will need individual treatment.