Well, the trap for anything, cannot be under the floor. It is poor planning and design to place the dishwasher remote from the sink, and not have a proper drain plumbed to it during construction. If you had a kitchen designer involved, I would read them the riot act.
But, you are stuck with what you have. How about a diagram or picture of the layout so we can figure out if there is a reasonable way to get this hooked up.