Hi CamiloChile, sorry I haven't reply before but I've been busy with other things.
Basically, you will need to remove both sided covers to gain the necessary access to replace the cable, but the stator assembly can be left in place in the center of the wheel.
Check out
this post which explains how to remove the covers.
If it's a rear wheel, the R/H cover will come off complete with the freewheel, so there's no need to remove the freewheel first.
There are also some nice pictures in
Magzy's wheel bearing replacement article which you may find useful.
Because yours has the internal controller, you will need to unsolder all the motor harness wires that are connected to the controller (The two thick battery cables and eight small wires ringed in yellow on the attached photo, but make sure you know where they all come from so that you can put the new ones back in their correct positions.
Remove any other clips or tie-wraps etc. as required so that you can pull the wiring through the small channel in the axle which runs under the L/H bearing. If the harness is not going to be reused, it might be easier to cut it off as near to the bearing as possible so there's less to pull through.
If the bearing will come off easily, remove it and then use a small file or sandpaper to remove any sharp edges from the machined slot to ensure your new cable does not become damaged.
When everything is nice and smooth, refit the bearing and then carefully thread the new cable through the slot as far as it needs to go to be secured in the same position as the old one was. Some washing up liquid may be required to help the wires slip through the tight gap more easily.
Carefully solder the wires onto the circuit board, ensuring they are secure and in the right place.
Make sure the wiring cannot rub against any moving parts and then refit the side covers making sure they are seated correctly and that the axle turns easily without and rubbing noises
(use a 10mm spanner on the flats of the axle if it's too tight for your fingers to turn it).
Then all you need to do is refit it to your bike and try it out.
Alan