[Gandalf Parker]

You can just select other nations and choose them to be computer opponent.

If you want them to ally against you then you can edit one of the map files. There is a mapedit.pdf in the dominions2/docs directory.

Choose a map you want to play and find it in the dominions2/maps directory. Lets say you choose the Aran map.

Copy the .map to a new file (such as copy aran.map to OurGame.map)

Open it in Wordpad or some other editor.

Find the line that says "#domtitle Aran"
Change it to something like "#domtitle Our Game"

Now scroll down to where it starts doing things like landname and neighbor and terrain commands. Insert lines for the AIs you want to be in the game.

The easiest thing (if you want allied enemys)is to add "#allied X Y" where X and Y are the numbers of the nations you want allied. Here is a list of them....
0 Abysia
1 Atlantis
2 Pythium
3 Man
4 Ulm
5 Ctis
6 Arcoscephale
7 Caelum
8 Ermor
9 Marignon
10 Pangaea
11 Vanheim
12 Jotun
13 R’lyeh
14 Mictlan
15 T’ien Chi
16 Machaka