World wrap, with player in center.

Hi

I'm totally lost and hope you guys can help me. I want to make the gameworld wrap on itself, or atleast the illusion of it.

Abit like old asteroids. but instead of the ship its now the camera moving (with the player) over the edge. And I only want to do it on the horizontal plane.

I'm trying to something like in this game. http://codeincomplete.com/projects/tower-platformer/index.html#flat

Where the player is in the middle of the world which is about 2 screens wide, and whenever he walks to either side of the world he always come back to same same spot.

And I would like to do this in a 2.5d platformer with physics, particles and so on. Is it possible? If so how?

ps. if I need to script it I would really appreciate some help as I'm not that good at it.

Thank you. <3