That's why I needed a picture to see just what it is your trying to get to.
If it's the coil stock fashia your trying to fix you do not need to go up on the roof, you get to it and nail it while facing it from the wall side.
This will keep a ladder on the roof if that's what your trying to do.
Qual-Craft® Ladder Hook With Roller (2481) - Ladder Accessories - Ace Hardware
I've been unable to find them at Lowes or Home Depot in my area so I order mine from Amazon.com
You attach it to the ladder and just slide it up the roof riding on the wheel, when it's over the peak just flip the ladder over so the hook holds it in place.