I've replaced several M-B hood pads. Here's what has worked for me:
1. Acquire the correct replacement hood pad - multiple sources exist.
2. Acquire a can of 3M Super Trim Adhesive.
3. Place a large sheet over the cold engine and fenders to catch the old hood pad as you remove it.
4. Use a plastic puddy knife to gently and thoroughly remove the old hood pad. Discard the residue.
5. Replace the sheet over the engine and fenders to catch any adhesive overspray.
6. With a helper, hold the new hood pad up to where you're going to adhere it to ensure that you see exactly how it is going to fit and look when you're done.
7. Follow the directions on the 3M can *exactly* to carefully apply the adhesive.
8. With a helper, fit the new hood pad.
9. Remove the sheet.
10. Admire your good work.
I recall the cost of this job (helper worked for "free") to be about US$65.00.