Frankly your designer (or builder) should have thought about this before now. Soil pipe routings are on of the important fundamentals in the design of a dwelling.
If they are going in the ground, this is normally done during the foundations stage. If the oversight (rough concreting below the final screed, or alternatively a system of block/beam) has been laid already it is going to be a devil's own job to dig trenches now to put soil pipes in. These then have to run to a manhole (personhole?) outside the property and to the sewer system. Again, all done before the walls are constructed, normally.
You may have the option of a macerator/pump system to overcome the issue. These things can be fed by any waste water (including the loo). They chew up all the nasties and enable them to be pumped (so uphill if necessary) through a small pipe (50mm say, not 110mm) into the existing sewage system. But even the macerator outlet pipe needs to be routed around the skirting somewhere.