Can't find the thing to attach to the lens again so you can bounce the IR, but it's something like a fast cap, only oblong in shape with a reflective surface.
Oblong so that the surface extends beyond the body of the camera so you can aim at it from behind.
You can probably alter a fast cap (
1101521 Op/Tech 52mm FastCap Lens Cap) and attach a reflective piece (at back front of cap so that when it is in open position, the reflective surface is pointing towards the cameras back) of rectangle on it.
Another easy way is just to position a mirror from the front of the camera so you can see the IR sensor from behind.