Hey. If you take off the covers where the wipers are, you'll find rubber grommets or a grommet there. use that to go through the firewall. It's the easiest place I could find. Hope this helps
I haven't taken the cover off yet, but I took these pics to see if someone can point it out to me..
'99 T.Green SVT #1925 yeah, its got a few mods 38,800KM and counting... MY SVT ALBUM