Hi!
My first piece of B&O was a beautiful BM1200, which came with original BV1200 speakers and... the original wallmount thingy! Only 35 euro's
It is a metal frame that slides into the little slots in the rubber/plastic paws (good english?) that are used when standing horizontal, flat on the table.
On this frame you can click a silver/alu colored brace-something that will hide the cables out of sight.
I'll try and make a picture of it if you like, the beomaster is at my mother's house right now so might take a while.
A sheetmetal plate that slides into the little slots should do the trick too, maybe even better.