What you should do is call Cabela's and act like you are going to buy another pair of waders just like the ones you tore the boot on.
Act stupid and ask lots of questions as if you're not sure you want to buy that product.
Let the sales person talk you into buying them slowly. Make sure and ask about the lifetime warranty at that time. NOT when you're standing there with a broken pair.
If they won't help you...then buy the new waders that are exactly like your old ones and when they come...swap and say that the broken ones came in the mail so they need to replace them.
I've never done anything like this myself but have heard this scenario before.
Somebody is going to point out that he'll end up with two pairs of new waders...
THAT is a very good thing if you hunt daily. Wear them on alternating days .