Yes, this is possible. You have to go to the ailist. There you have to write a new ai group. This has to look like this:
Then you have to go in the Omsi Editor and load the map X10. There you have go to the tab "Tracks and Trips". When you click on this you find the button "Edit timetable". You have to click on this button. Then you have to select line 115 and change the Group on the spinner "ai veh. group" to your group which you wrote in the ailist. Then you can save the map and close the editor.
I found that incredible confusing