Originally Posted by Bonzai
Another possible toilet solution that does not require breaking up the floor is a Saniflo macerating toilet. If you look for this on YouTube you'll see an installation video that explains how the drainage works. It does not use a regular 3" drain and no need to open up the concrete. However the toilet with macerator retails for around $850 from what I can tell compared to leas than half that for a regular toilet. Probably going to install one for a client in their condo as no place for a regular drain.
First time I've heard of a macerator toilet so after reading your post, I did a web search. Found this youtube This Old House video that has a great description of that kind of toilet. Here's the link to save others from searching:
Looks like a great solution to the OP's question. In his case, he could just tie the output of the macerator toilet to his existing laundry room drain without having to run any pipes in the attic.
Just be sure the kids don't flush any rags or toys down the toilet .....