Blether a BFO hole/access channel from top or bottom with a length of conduit or a s4itty stick. Cut hole, fit box. If too thin for DL box fit a 25mm metal box with those annoying little wings/lugs adapters that fall off.
Fit cable and apply applicable Regs 50mm, RCD, Causal Matrix, OCPD, Dalek Invasion Yahda Yahda Yahda.
No different to any othe demountable partition walling really... :coat