SNES Save Battery Replacement

Okay - I know this is most probably suicidal, but I Have to replace the save battery in my Lufia II cart. It’s been sitting idle for Ages now, and I can’t do anything because I can’t save!
I have a CR 2032 battery, and the soldering iron, but do not know Exactly how… (I’ve read through tutorials and that, but don’t feel so confident after having just read that). If someone who’s done it before could guide me through this, that’d be AWESOME.