I did this already. There is a large 2" diameter grommet between the cabin and the engine in the passenger footwell behind the battery. Take out the battery and the battery mounting bracket and you should be able to see it. There are several premolded "nipples" that can be trimmed off to open them up. There are already a few wires passing through the grommet with several spare nipples available.

Remove the side panel (if I remember correclty) in the footwell and pull the carpet back to access the grommet from the inside.

Let me know if you have more questions. I'll look to see if have some photos I can put in my album.