I'm not in a position to be able to check at the moment, but from memory you'll see a little light unit to the RHS of the glovebox interior. What I did was to carefully prise this out - with a small screwdriver - into the glovebox (with its cable still attached), leaving a rectangular hole. The body of the glovebox is a kind of stiff fibreboard around 3mm thick. In the furthest corner of this rectangular hole I carefully cut away a little of the material with a sharp Stanley knife (mind your fingers!), just enough to enable the cable of the box to pass through without being unduly pinched when the light is refitted.
Possibly not the most elegant way of doing it, but fairly neat and because of the lip of the light unit, leaving virtually no visible damage should you wish to remove the cable in the future.