Simple two step process:
Step 1: Ask your Local Orthodox Jewish Rabbi.
Step 2: Do EXACTLY as he tells you.
In all seriousness there are numerous details, all of which you have left out, that affect the answer that you will be give. Second to that there a variety of opinions, especially in relation to Pesach, that will greatly change the answer that you will be given.
1) Can plastics be kashered?
2) Can non-stick coatings be kashered?
3) Can modern ovens even be kashered(there are authorities that say no) and if so how? For instance the Eida HaChareidit insists that the torch also be applied to the seal and window(if any) in the oven which invariably destroys them, and renders the oven unsafe(at best) to use).
When you consider the extremes in opinions, and everything in between, this is a question that really has only one possible answer: "Ask your Rav."