Depends what stage your at.If your room is completely finished it will be difficult to fish the cables throw all the studs with the plaster boards still on.
Plaster boards are only a few quid each so if its feasable I would pull the old ones off,put your cable runs in......and,in the process work out where your wall mounted stuff needs to go and place 18mm sterling board strips so you have a fixing when the boards go back on.
If you get tapered edge boards you'll be able to tape and joint instead of skim...a quick sand and paint job when it dry...put your skirtings back on and hey presto job done.
Realy simple..cheap and done in one weekend no probs..
I've just build a timber frame extension and this the way I did my runs in the home cinema room.nice and neat and not to difficut at all.
chow