This mod will make you 3rd and 4nd door manual and 2nd door will open by CG too. If you dont want to have automatic close door, just find in constfile of door Automatic Back Door Time and change all 3 parts to some big number like 1000.
If you want to have entry for all doors, just open .bus(not KI), add to name of passenger cabin word all and in .osc of door-3 do same, add word all. Like this:
passengercabin_12C_2doorall.cfg
door-3all.osc
Now passengers will entry and exit through all doors.
There is function for all doors but not button for it.