Is there a way to make SEIV more challenging?

[Fyron]

Is it possible to use the "improved AI" files of the TDM mod for the AST mod too or not.

You would have to edit them to be able to use the new technologies and other items in AST properly. The TDM AIs are designed for the stock, unmodified game.

You might want to look into the Star Trek Mod, which has far more of a Star Trek feel than AST. AST is basically stock SE4 with some light sprinklings of Star Trek. The Star Trek Mod is more of a total conVersion mod. Note that they were made primarly by the same person, Atrocities.

http://www.astmod.com/startrek/stm.htm