I seem to recall seeing a spell that activates multiple wands simultaneously...

[emoplato]

Not to be a wet blanket, but in reading that spell I fail to see how it would allow anyone to activate more than one wand at a time.

It lets you activate one at a distance (specifically medium range), but it says "all other conditions" must still apply. That means that you need to speak the command word to activate.

Mechanically I don't see any way to Chain Spell those together, since each will be specific to the individual wand or staff in question.

Now I'm a bit hazy on Chain Spell: Is that a Feat or a spell?

If it's a feat, wouldn't it just be easier to use Dual Wield Wand, and save the spell?

Chain spell is a metamagic feat(3 levels), traditionally it is suppose to be used to give ranged single hit spells to jump to multiple targets within thirty feat up to your caster level. The limitations of the hit are based on 1/2 damage from the base hit and reflex save or reduced DC by 4 if it doesn't deal damage. This spell doesn't do either of those things but still is a spell that qualifies for the feat so it doesn't have those limitations.

 

[Greenfield]

Then it's up to the DM. The spell itself implies that the command word or spell trigger still needs to be supplied, so unless all the wands had the same spell trigger I don't see it. Your DM, on the other hand, might.

Have you considered an item to do the job? There's a Rod that can hold up to three wands, and allows you to activate one, two or all three simultaneously.