There will never be a trainer for this game. Ever.
O´rorke have made that very clear. However you dont need it as there is an excellent alternative, or rather two:
1) check out the ultimate Wiki on supreme ruler - there you will find the cheats which can tweak some of the games parameters.
2) Check out Battlegoats forum for supreme ruler - there you will find the very excellent trainer for supreme ruler - be aware however that this trainer only works for version 6.7 and the present version is 6.8. Its because its creator Anewbies is very ill and maybe dead (no one have heard from him in months).
What you do is install the game, go to the forum and get the 6.7 mod - install the trainer and presto you are up and running !