Thanks for the guide! I used a light duty heat gun to soften the battery adhesive. Use great caution if you try this method, you can easily damage anything plastic so I used the MBP bottom to shield the keyboard bits. I heated one cell at a time until it was slightly uncomfortable to the touch, then waited a few moments until the heat softened the adhesive underneath, then carefully use a plastic card to slide under and pry free. It took about an hour to remove the battery and all remaining adhesive. For the remaining adhesive I used "GooGone", being very careful.