Didn't me and someone else already answer this question? I use 252 Atk/248 SpDef/8 Spe to keep the 8 Spe the analysis likes for no apparant reason and the 248 SpDef ensures maximum special bulk. If you don't want the 8 Spe, then put it in SpDef and HP.
I guess I would ask what you want the Scizor to be able to do? Is there a reason you are using it over something like Empoleon, which is far bulkier, has more resists and no 4x weakness, and still has great offenses (including STAB priority) for your special tank? Other options for special tanks with decent punch abound, including Jirachi, Celebi, even Vaporeon.
A standard CB Scizor is not even 2HKOed by Starmie's unboosted Surf (43% max). Shadow Ball from a max SpA Specs Gengar also fails to 2HKO (44.6% max). Against a Charge Beam Jolteon, standard CB Scizor can switch into +1 Hidden Power Grass, then live the +1 Thunderbolt and OHKO with Superpower. That is some pretty decent special bulk right out of the box. Adding more mostly means living Fire moves, and good luck with that. Even a max/max Scizor is OHKOed by even a non-STAB Fire Blast from practically anything, including BaitTar, Lead Azelf, and even a minimum SpA Salamence.
So again, what role is this thing filling? We can help you optimize EVs to a task, like minimum needed to live a Fire Blast from Scarf Flygon, for instance. But for the most part the EVs in the analysis are pretty good. DDRMaster's suggestion of moving all of the HP to SpD is ok I guess, but I'd rather have the extra bulk against EQs and Waterfalls, and Fighting moves personally.