if you put them through behind the battery they are really easy to access hence most people doing it that way.
You should be able to get in under the passenger footwell without any dismantling but if you need to...
-Take the passenger door sill cover off (looks like a hockey stick), it just unclips if you pull up.
-undo the 2 nuts holding the left hand footwell cover on, one at the front and one on the back wall
-undo the screws holding the cover that has the drink holder (or money tray) in it [cant remember how many there are but just hunt around for them)
that would give you clear access of the area