or atleast triggering it? i gutted one of those birthday cards with the sound device in it because i thought it'd be a good thing to learn to get the sound out of them. but with no help from google im stuck.
If you want to activate one of those mecanisms via a processor then you'll need to either use a relay to do the equivalent of pressing a button.
Another possibility is to link the ground of both you processor and the card chip. Then with a 4K7 resistor in series you could probably connect an output directly to the card but without seeing the circuit from the card up close I can't give you more accurate instructions.
Post a photo or 2 of the circuit you pulled from the card and the battery it runs on. Is it a 3V battery?