I just changed the car key “fob” batteries in two Honda vehicles (2005 and 2007), and thought I’d share the screwdriver and batteries I used:

• Great small screwdriver set:  Boxer 30 Pcs 4mm Precision Screwdriver Set
• CR1616 batteries:  Maxell CR1616 Lithium Coin Cell (5 Pack)

I would attempt to explain the process (which is pretty intuitive), but someone already made a great instructional video: