One of the very worst things you can do for any baseball glove, is soak it with glovoleum or any other oil and put it in the oven. Lexol is much better for the leather, and should be used sparingly. If you're going to spend big bucks and buy a great catchers mitt, you should also take the time to break it in gradually, not go for some quick fix that'll break down the leather prematurely.
One of the best things you can do is to properly treat it with Lexol or other quality leather treatment, and then go sit on a bucket and catch hundreds of balls from an Iron Mike. That'll help break your mitt in faster, and you won't be damaging the leather with some quick fix.