i have a mk1 punto and i fitted my amp wire like this.
(the interior is simular so its basicly the same way)
> connect the wire cable to the battery
> run it around the inside of the engine over to the left hand side
>now near the bonnet hinge there will be a small hole into a dark space
>remove the screws in the wheel arch, u know the plastic case above the wheels to catch the dirt.
pull this out a bit it will let light in
>push the wire through and look in the wheel arch, u will eventurly see the cable and be able to pull it down.
>now pull the carpet up from behidn the pedals inside your car
>there will be a rubber plug pull this out and feed the wire through this hole.
>now as you get in the door along the bottom edge is a plastic cover unscrew this and behind it will be a load of cables, just pop the wire in with these.
>then u need to unbolt your backseat and unscrew the inside back side pannels, (just the bottom one so that you can pass the wire under it and into your boot.
>then screw and bolt everything back into place
hay presto the wire now goes from engine to boot.
but dont forget the other cables need to go with this.
does this help