They go from the passenger side handle location, accross underneath the backseats, behind the passenger rear trim panel while passing through the metal cutouts into the boot. From there it splits into the main latch for the petrol door, and the rest goes to the boot latch location.
i have done a bit of a write up on this a while ago http://www.micra.org.uk/threads/aftermarket-boot-fuel-remote-release-fitting.49459/#post-508484
the remote lever is obviously mounted on the drivers side the cable then runs under the back seat across the floor to the passenger side then over the top of the rear passenger wheel arch to the fuel release then onto the boot locking/ release plate