Actually, removing the hood is serious overkill.
Open the hood all the way, and remove all the remnants of the old pad.
You will need some 3M adhesive remover to get the last of it. If
someone has used Liquid Nails or something similar, you will have a job
on your hands as it really needs to come off. Don't use a metal
scraper, you don't want to remove the paint.
When the hood is pretty clean, fit the new pad, using a broom to hold
it up in the center. Make sure it's located properly (it goes under
the metal at the edges), then fold down the top half and apply three
thin coats of 3M trim adhesive. Use only the cans marked "8090" or
High Temp -- the regular stuff won't stay up. Coat both hood and pad,
noting that the pad needs only a light coat -- if you fill it up, you
are using way too much. You need a nearly continuous, thin coat only.
When tacky, press the top half of the pad in place firmly -- best to
just let it touch to start with as it can be removed unless pressed
hard. Once in place, fold the bottom half up and repeat.
You should need less than a full can of spray adhesive to attach a new
pad to a clean hood. If you get the low temp stuff by mistake and the
pad falls down, you can just repeat with the correct stuff and the pad
wills stay up -- my brother's has for at least two years now.
Peter