It's not as complicated as you might think, but there's a lot of trial and error involved. Your first step would be to open up the .bus file for the bus you want to alter the views for, e.g.
digibus_phantom_4speed.bus
using Notepad/Notepad ++ or something else.
In the .bus file, you'll want to look for something along the lines of this:
View attachment 65941
The views should be numbered as you can see in the image, however the labels aren't always in English (remember my example uses V3D's bus!). You can use
this Steam link which tells you what each value does under each labelled view. Then its just a matter of loading the game up and realising that you've moved the view into the staircase ????. Hope that helps!