Product review (5 stars): You can do this!
What looked on the surface as a daunting task was really pretty easy. The door of a freezer is designed to accept the seal, so you're not breaking new ground. Two things made my task easier: a power screwdriver with the correct bit (mine was a 5/16" hex socket) and a ratcheting cargo strap. The power driver allows you to rapidly tighten the screws evenly (you should loosely set them, then snug them up as you work your way around. There are several 'how-to' clips on YouTube) and the cargo strap helped by holding the door tightly closed to help the seal seat itself (it ships in a box much smaller than the door, so it needed a little pressure to straighten out completely.)
It took me about 15 minutes to complete a job.