not familiar with that specific vehicle but most have a rubber boot where a large group of wires pass through the firewall into the cabin. poke a hole in that and slide your power wire through.
...or just grab yourself a drill and make your own whole in the firewall...just be careful to plan out whats on the otherside (i recommend going from hood -> cabin so you have less chance of drilling through anything important like your master cylinder //content.invisioncic.com/y282845/emoticons/nono.gif.eca61d170185779e0921b0faa9704973.gif )