Custom keyboard configuration (suitable for up to 5 door buses etc)

Door bindings 

Open/close all doors door_all Open/close first door (or incase of MAN SD buses and some other first door first part) bus_doorfront0
Open/close second door (or incase of MAN SD buses and some other first door second part) bus_doorfront1
Open/close third door bus_doorfront2
Open/close fourth door bus_doorfront3
Open/close fifth door bus_doorfront4

Custom keyboard configuration

Here you can download Gameburrow's custom keyboard configuration that has ll these keys mapped:
https://cloud.gameburrow.codes/s/Xi3oWKaArtKrwq4

Changes from default:
Shift + Num 0: Open/close all doors
Shift + Num 1 - Num 5: Open close 1 - 5 doors
Shift + Num Enter: Station Brake
K / Shift + K - Kneeling toggle (for some buses just pressing K toggles/untoggles, for some you need to press K to toggle and Shift + K to untoggle, for some this bind doesn't work at all)

Alternatively, if you want to add the keys manually, you can edit the following file OMSI 2/inputs/keyboard.cfg:

[entry]
door_all
82
2

[entry]
bus_doorfront0
79
2

[entry]
bus_doorfront1
80
2

[entry]
bus_doorfront2
81
2

[entry]
bus_doorfront3
75
2


[entry]
bus_doorfront4
76
2

[entry]
bus_doorfront5
77
2