I bought this light too and I am very happy with it so far. I started out hanging the battery pouch from the TT but the straps weren't long enough to really secure it, so it 1) swung back and forth annoyingly and 2) brushed my legs when I was up sprinting. You can however tuck the coiled part of the cable inside the front zipper on the pouch. If you constructed strap extensions -- maybe 4" long x 1/2" wide nylon strips with snaps-- you could strap it along two axes between the head tube and top tube, and that would be pretty clean.
The method I hit upon is to use velcro tie-wraps to strap the cord along the bottom of the tt and tuck the battery into my pannier. Its a bit of a stretch with the stock cable, but I ordered up the 4' non-coiled extension along with a second handlebar mount for my fixie.
One other comment about this light -I orderd the 12 degree flood but I'm going to see if they can send me the 6degree spot reflector so I can compare them side-by-side. I fear the flood is too wide and I'm both losing some distance as well as unnecessarily blinding the oncoming traffic ... YMMV