I have my Sirius tuner underneath my seat and have an easier solution than to remove the seat.

1) First, make sure you connect all the wires to the tuner because once you move the seat back you'll have very little room to maneuver anything or connect any wires

2) Now, slide the tuner on the floor from the back all the way to the front trying to keep the 2 cables attached to it in front of the tuner. Start to move the seat back into the normal position. The tuner may get caught on the seat but you should have enough room to get your hand under the seat to grab the wires and/or tuner from moving back with the seat.
Once the seat is back you'll have some room to move the tuner around and pull the wires through the front area under the seat.

3) It's time to start hiding the wires and connecting them to the unit. Right around where the cig lighter is on the passenger side is the best place to feed the power/ground and output wires through to the head unit. Though they'll be sticking out a little, you can easily push them in the center console paneling once you're done.

Take your hand and get an idea of where the crease is on the paneling mentioned above, you should be able to get a finger through which is enough for the wiring. Poke your finger through and work the wires through. Now you'll be able to feel the wiring as it goes back behind where the head unit goes. Pull the Output wire through where the rest of the wiring is to be hooked into the back of the unit (this wire is typically thicker and will make pulling the thinner power/ground wires easier). The same goes for the power and ground wire (should be Yellow and black, respectively). Once you have the wiring in place and the output wire in the back of the head unit, fire up the battery and test the connection.

Once, done push the wires into the center console paneling until you hit a dead end and the only person who'll be able to see it would be the passenger but it's not all that intrusive.

Now you could pull up the carpeting and make holes for the wires but as long as I can't see the wires that's all that really matters. I'll take some pics of how i have mine tomorrow and post it up if my instructions weren't great or that visual.