It is possible, using a combination of mods and EA debug commands, to add Sims to custom worlds using Edit-In-Game in the Create-A-World tool (CAW). Please check out the discussion page for less substantiated research and areas to look into.
1.2.4.4 A Warning about Ghosts & Mummies.1.2.4 Step Three: How to add premade Sims.1.2.3 Step Two: De-fuglying and clean up.1.2.2 Step One: Using the Make Sim command in Edit-In-Game.
