According to this project plan on IKEA Hackers, simply unscrew the front panel of any old stereo or vinyl player (pictured above is the Dual HS37), remove the knobs, and drill some holes to fit the GRUNDTAL hangers into place.
Also Recommended: Stain a piece of walnut wood (about 1" thick) and screw the panel into it. Doing so allows for more flexibility when it comes to adding wall-mounting hardware, and if you happen to be mounting onto sheet rock, be sure to look for them studs. You'll be surprised how much weight a couple of coats can put onto a wall.
More info: IKEA Hackers