I wrap the cable around the steering column (as GaryG showed me long ago). So it comes out of the OBD2, does a 180 so the cable comes towards the driver, then up and below the left side of the steering column. Tucked out of view it goes 360 degrees around the column then up to my dashboard. I have it wedged in just to the left of the speedometer, covering up the eco-tree. Others on this thread have found more professional looking ways to mount it..
Oddly enough I would have rather had a thinner cable. The cable has all 16 wires in it but I only need 4 of them. I cut the other 12 at an angle so they are all slightly different lengths then visually check that none can short any other.. then I wrap it with electrical tape, solder into the LeafDD and strap the two zipties for strain relief. It would have been simpler (IMHO) If I had just the 4 wires I needed.. If someone (not me) takes this into production down the line, maybe they can secure custom cables. For this little 150 piece hobby I've just been buying the cables from obd2cables.com.