Im new and have no idea, i saw something and want to know how this was made. This viewtopic.php?f=2&t=3631.
How is it possible to do this positions or did i miss something ? I think this was made with mods but which ? Thanks.

depending on what mods you are using you can give a command to make them just turn into a ragdoll. Most of them you give the command of "RELAX" and some its "REST" I hope this helps.

But can you fix the Position after that or does this completely disable collisions ?

You grab the girl and drag her to where you want after that. Click basically anywhere but her tits, pussy, and ass, as those will just make you move her flesh around.

She will not make any effort to stay in the position you want, however, so you need to counter gravity as you would with an unconscious person, though there's a bit of stickiness to the limb positions, so it's not a complete ragdoll situation.

I expect later versions to improve our ability to do things like this, where the girl will maintain the position you set (within the limits of reasonable physics), but for now you're just going to need a bit of patience to get things where you want.