i would assume that you would just be running new wires from engine to trunk just like running an amp ...my $0.02,but i dont know how the pros in here do it

 

It's basicly running new wires to the trunk but you have to:
1) Find a good place to mount the battery. If you do ghetto style, you might find a battery flinging around or slapping you in the back of the head during an accident.
2) Consider a sealed type to avoid nasty acid leaks
3) Find a marine battery case to hold it down and further seal the battery.
4)Use some thick *** wiring to reduce the line losses.
5) Find a very good ground in the rear or run another ground to the oem ground site.

 

everything jeff said but one more thing buy the optima battery I love mine its the greatest thing in the world it ran the car for 3 days with a failed alternator, not only that but no more nasty battery corrosion either!
Goodluck!!!!!

 

They sell kits to do this. Call Nopi or check out your local performance store, Auto Zone may even have a kit. With stuff like that, it's usually all the same.

 

Go to http://www.summitracing.com/ and search for "battery trunk" and you will come up with 3 kits.

 

Yeah, I used this kit from Summit Racing when I relocated my Optima Battery to the trunk.