@privateer:
Thanks. I was aware that *.act are simply .dll files, since I already changed Sh3Sim.act and EnvSim.act to change e.g. torpedo reload and weather. These files also have an regular ModuleEntryPoint (DLLMain) that is called by the system loader at game load time, what is a nice place to add some executable code.
I also programed a separate hsie.act which was loaded successfully in order to overwrite some executable code of sh3.exe (Dll code injetion).
My problem is to completely understand and re-engineer how the AI works that is coded (probably) in Sh3Sim.act. I can find there the Strings
cmdr_AIship & cmdr_AIAirplane, which could indicate that the AI is stored there. I also found huge jump-tables which could contain the addresses for the appropriate AI-routines. It will take long time to understand how they work and to change them to have something like
cmdr_AISubmarine.
Importing from SH4 is a good point. Does SH4 have AI-Submarines?