Step #1: Wear some safety glasses. I got a big ol' peice of rusty junk in my eye when I was working off my back doing this.
Step #2: Are you opposed to swearing? If not, good. Because you'll be doing a lot of it.
Step #3: Remove all obstructions so you can access the little bugger from underneath. That means all air ducts, wiring, etc...
Step #4: Get yourself some Advil because your back is going to be more crooked than a politician from laying on the trans tunnel.
Step #5: If you have abnormally long arms (like a Shaq-long) you may be able to remove your glove box liner and access it that way.
