This is my solution to finding a good location for the IR Eye within a BV4 and 7.4 combo.  Visually, as well as technically I think the eye should mount in the same place where the 7.4 speaker should mount (Directly below the center of the screen).  I've found that the sandwiching of the three seems like a visual compromise unbecoming of the B&O aesthetic.  Placing the IR Eye anywhere else in the room produces poor IR performance due to interference from the plasma (even with the IR protected version).

As these (poor quality camera phone) pictures demonstrate, I set out the other morning to see if I could mount the IR Eye's receiver invisibly within and behind the grill of the 7.4.   The end result worked really well.

This is where I had the eye mounted after I got my 7.4. It is located on the wall to the left of the screen.  It seemed like a good idea at the time and didn't look half bad, but it got a lot of interference when the screen was on.  Plus, it drove me nuts having it next to the light switch and not being able to control anything with it like in all the other Link rooms.

As you can see there is plenty of unused space behind the grill although it's not very deep.  You can see on the wall where I previously had the Eye mounted.

Here is the IR eye with the case removed.  You have to cut the two ground (GND) cables to remove it completely from the case.  I've also removed any extra plastic components that got in the way of the unit being flush on the face.  I spray painted the center of the circuit Matte Black (While being sure to mask the actual lenses with tape).  I tried without painting but you could still see it behind the grill.  The sides that are not painted will be covered with black foam.

Here is the Speaker grill.  As you can see I've cut out two of the plastic spar parts.  They cut easily with a Dremel type electric hand tool with a cutting blade.  If I could do it again I would cut the wider spar closer to the size of the circuit. If you cut it just right you can use the cut spars to clip over the edges of the circuit to hold it in place.  Also, it's not necessary to cut such a big hole into the foam.  That was just me being sloppy trying different positions during the testing phase.

As I found out, even the black painted surfaces of the circuit presented a slightly different sheen behind the grill that could be seen from certain angles.  Having it foamed as seen above rendered it virtually invisible.   I was lucky to have some adhesive foam laying around. 

 Here is the circuit in place. The metal mesh grill seems to have little or no impact on IR performance regardless of direction or position of the remote in the room.  It actually worked pretty well from behind the foam as well but not nearly as well as with the foam cut out.  Obviously, I wouldn't plan on using automatic image control in this configuration.

I found the simplest way to run the cable was to make a small notch at the bottom of the grill where the cable can be run out and fixed flush to the underside of the speaker cabinet where it would be invisible except to someone looking under the speaker.
 

I decided to remove the sliding grill track from the front of the cabinet.  It could be mounted with it but it was very tight and I was afraid I would damage the circuit components when sliding the grill on and off.  Structurally it didn't seem to make a difference and it was actually a little easier to attach the grill without it.  Don't remove the clip at the top of the slide.

Here is the end result.  I will probably raise the BL7.4 to be almost flush with the screen as with the BV 7-40.