[Suicide Junkie]

Well, the easiest way, if you want the human player to be the newborn race, is to start a game, and play the first two years without researching tech.

You could build colonies, ships and lots of units so the player won't be totally crushed when the AI sees how weak you are.

Keep lots of savegames, and use the save just before you meet the AI(s).

Move the savegame into the tutorials folder, and copy "tutorial_settings.txt" and "tutorial_text.txt", renaming them appropriately for your savegame.
Edit your copy of those two files to be appropriate to your game, especially the second one. In there, you should have the game display a debriefing from your ministers, detailing the situation.
Remember to set the date on those Messages to the current turn, and not the first turn. Otherwise you'll never see them.