Isn't all this talk of trunking, hole drilling, etc., missing out the fact that scart cables usually come with lumpy plugs attached to both ends? Or do more people than I would imagine happily unsolder/resolder the plugs?
As has been said, you should use HDMI or component leads.
However, if you must use a scart socket or one or both ends, then you can use a lead with RCA/phono plugs on it to feed one at a time through a small hole, then plug them into an
RCA-SCART adaptor.....