There is really only one way to do that, you have to break up the slab in the areas that you need to put your pipes, if it is on the edge of the slab you might be able to get away with digging under it.
Unfortunatly the only way to fix plumbing under a slab foundation is to break the concrete, the new plumbing needs to lay on gravel also should be insulated prior to putting concrete down.
Mark on the concrete where the center of drain and supply lines will be located. Mark 1/2 the diameter of the pipe plus 2" to each side of the lines. Cut the slab along the outside lines. Jackhammer concrete from inside the cuts. Install plumbing and then repour concrete.