If the interference (whine) is coming from the fuel pump, the only way to effectively fix the problem is at its source (the fuel pump). As already stated, nothing else will fix the problem. The only right way to fix the problem is to solder a capacitor between or as close as possible to the fuel pumps electrical terminals.
My 04 X has less than 7000 miles on it. Other than adding to (off road lights, aux fuse block, etc), I'd much rather not screw around with any existing wiring for fear of having some sort of problem later on and then being told it won't be covered under warranty cause I dicked with the wiring somewhere.
Although... here is an idea I had.
The fuel pump seems easily accessible under the rear seat. I haven't checked yet but I'm guessing the power wiring is connected to the fuel pump with some sort of male/female connector. If it's possible to get the same male and female connector, a small 1.5 or 2 inch wiring extension cable can be made with the capacitor soldered between the power leads of the extension cable. One end of the extension would plug into the fuel pump and the other end would plug into the existing wiring. The capacitor won't be wired directly to the fuel pump but at least there will be one wired close to it. Hopefully it would help/work.
Gene