{snap caster Mage} + {equilibrium}. Bounce the Mage as soon as it comes into play
Equilibrium's trigger will resolve before Snapcaster hits the field. Snappy won't be a valid target.
Edit: It even says so in the Gatherer rulings.
The only way for this to work is if you trigger it off another creature and drop Snapcaster in response to the trigger.
Or just have 2 snappies