I dont think you can.
I have not said in any moment that I am the one that can make it. The only thing that I say is that it would be interesting to be able to see how it is that BIS makes this. I have been trying with the command setvelocity. And I have seen myself that, after it applies to an airplane the AI returns to their previous speed. There are other commands with those that the same thing happens, and that is something that you have discussed here. I repeat that, if a look could be taken to the autopilot scripts of BIS. One could see how it is that they achieve these things.
addon makers will include the required functions in there addon. Then there would be no additional files needed.
I believe that you have not understood the idea, what I am outlining is to modify in some way the original scripts so that they work like it should be.