Hmm. The ideal weapon someone else would probably have to point out (I hate WW and its silly breakpoints), but I believe it may well be one of the polearms.
Obviously Superior and Ethereal (+15% ED, base damage +50%).
Armour: Well, if you wanted perfect, 160/60max

- you'll never find those in SP though. Besides I seem to recall these don't work properly anymore. Best bet would probably be a Shaftstop (PDR), Duriel's Shell (CBF, resists), or Enigma (+2 skills, teleport, other very nice bonuses) if gear is really no object.
Shield: None on the primary setup but you'll probably want a Rhyme or Tiamat's Rebuke on switch. I'll tell you why - Iron Maiden. Put a Steel Short Sword on switch and smack away when IMd, or you will die. Other options for switch include the Buriza, of course... but you're a Barb, you should smack things!
Other gear: fill-in-the-gaps stuff. Any holes you have (resists, life, etc) can be patched here. You may consider adding more damage jewels in a helmet if you have them, but that's up to you really.
Merc: Act 2 Might. Holy Freeze doesn't help you that much since the merc is an idiot, Defiance is nice but you lack a shield for defence, Prayer, Aim, and Thorns do nothing for you... so rely on the old 'a good offence is the best defence' strategy. Besides you'll want to squeeze every last point of damage out of that BotD!
Merc weapon: Doom. Combined with Enigma's teleport, you can dump your merc close to a pack while you WW through it. I shudder to think of the rune cost thus far though...
Merc armour: Shaftstop (inevitably). Mercs need PDR because, well, they just keep getting hit... socket it with an Amn or Sol, maybe.
Merc helmet: Harlequin Crest for +2skills and PDR, among others.
Only thing with this build is that it is horribly, horribly expensive.
Stats:
Enough Str/Dex for gear
Rest in Vitality
Skills:
20 WW
1-10 Nat. Resists
1-20 Iron Skin
20 BO
1 BCommand
20 Shout?
I haven't played a WW barb so can't be too much help with the placements of skills and tactics, but there are a few people around who can be more helpful.