if you pull the head unit out and get a torch and shine it from underneath the passenger footwell upwards towards the gap in the dash, then look through towards the torch you should see a path in which to thread the cable.this can then be guided down through the gap, no easy way to do that, just patience and luck!
then once its through get your head underneath the glove box and im guessing there will be some kind of gap for you to feed the cable through into it.
alternatively you coild take out the ash tray/coin pot which pulls up with the lid open, guide the cable down there and then have it coming out right in front of the gearstick, thats if you want to have your ipod mounted on the dash so you can see it etc.
its up to you!
about the cables...if you look into the gap where the head unit should go, with it pulled out, id call it the back left bottom corner of the recess, on my car there is another recess going down where i have put most of my cables, and the fuse for the head unit, once i had everything as i wanted i just pushed my hand in with the unit out and squashed all of the wires down and then slotted the unit back in!
also, depending on the length of the cable for the ipod, it might be a good idea, if you are going to take it to the glovebox, to pull it all the way through the dashboard, but before you thread it into the glovebox use a cable tie and just wrap up what will be excess cable and tie it fairly loosely to another cable under the glove box or anything a cable tie will fit around, this means you wont have a few feet of cable in your glove box in the way, and also it wont hang down for your passengers to get tangelled up in!
sorry mate, bit of an essay there!!
