I usually just start with finding out if there is a modding community for the game I'm eyeing. That often means there are tools to easily extract meshes and textures from the game, and it's like Miros said - when you have the mesh as an .obj and the texture, all you really need to do is edit it to fit TS2. There are also a bunch of programs out there that take a 'screenshot' of the game you're playing, saving the environment and all the models and textures in it, making you able to import it in a program like 3DS Max (3D Ripper comes to mind). It's a bit of a pain to extract the part you're looking for from that jumbled mess.