Alot easier than you might think dealer and even good Indy mechanics will tell you it cannot be done, I do it at $50 a pop for friends and people who dont want to buy another key you just need an EXACTO knife and a glue gun and you basically separate the front of the key from the back of the key pop in a new Watch battery CR 2025 I think and glue gun it back together NEATLY!!!
looks good as new just saved yourself a fortune. Good luck and cut carefully dont hit the circuit board too hard or you might cut off a transistor :-)
*This is for informational purposes only, I am not responsible for any keys that dont work if tampered with*