Aside from the possibility of Epic Spectacles of Spirit Sight (which if you have a Staff of the Petitioner, or are willing to switch between a Dreamspitter and an upgraded Death's Touch, you don't really need), Goggles is likely the best spot for it.
I use goggles for SP ConOp plenty. I can swap to Tharnes if I'm not getting hit. HP ConOp I tend to move around, but goggles is still good.
Ghallanda - now with fewer alts and more ghostbane
Goggles are quite common, but if you plan on doing any melee damage consider using Tharnes instead. The to-hit bonus helps, and if you're doing autocrit damage you'll get bonus sneak attack damage.
Since the OP is running a Wizard with Skiver I'd suggest bracers. Casters mostly use this slot for the Bracers of the Glacier. Archmagi is covered by your Skiver, the guard is useless since you can self cast, so if you can afford to lose the spell penetration for your disco balls this is a good slot.
Moved to Guild Wars 2
As mentioned, goggles are a common slot. Bracers and boots can be pretty accommodating as swap slots.
The relative merit of con-op depends largely on your play style. If you spend most of your time hopping like a bunny rabbit trying to not get hit, it probably won't do much for you. If you're standing in a firewall swinging a greataxe, con-op + torc is indispensable.
hmm i put my Con-Opp. on bracers (hp item)
goggles is a given for hp or sp (you can get con-opp. either way)
next slot is trickier, bracers contains some nice stuffs, most notably bracers of glacier
cloak is a popular slot, but you might want to get an epic envenomed cloak later (not necessary, cloak is probably the best slot to put it on)
it is also possible to put it on a necklace if you dont have a ToD necklace set, or ?gloves? (someone told me it couldnt be done, but i thought you could put it on any item?) (if you can, you might not want to, as you might get a vile blasphemy gloves, and switching out items that give you sp/hp is something i dont like :[)
dont put it on boots, i wouldnt like losing either 150sp or 45hp for the hardest boss in the game
As of now (according to dev's this is supposed to change in the future at some point) the conc opp from a weapon
and an accessory both proc individually. This means depending on how much larges you're willing to use it might
be worth to get both a weapon and an item. I personally have goggles conc opp bracers pos/pos/pos with hp.
Depending on how much you're willing to swap this works very well I pretty much never use the epic ornamented
dagger since amrath clickies/eardweller get you more damage and I very, very rarely run out of them. Even in fairly
long quests with a lot of nuking I find I'm left with at least one to two charges of clickies before a shrine.
For bracers the only thing that competes in my mind are the bracers of the glacier but as someone pointed out
with amrath belts or skiver for archmagi and petitioners staff for spell pen they don't really do all that much. Boots
are another slot that is fairly empty but I usually reserve that for swap on the off chance I have to stay close to
horoth for wf healing.
Also as someone pointed out the sp gained back with torc+2 conc opp items is pretty good. If you have a nice shield you
can easilly get 800+ sp back in a matter of 1-2 mins if you can pull enough mobs to aggro on you.
Just my 2 copper,
Rawel
Save your larges. Con-op is VASTLY overrated.
Torq however... Love the torq. LOVE IT! OR ELSE!