A better approach is to insulate the roof slope above the attic.
How to insulate a single story attic.
Lay the batts across the ceiling joists covering the existing insulation.
Press and tuck the edges of each part of the blanket to make sure they fit snugly and that there are no gaps between.
The traditional approach is to insulate the kneewall and the attic floor behind the kneewall.
Pull the wiring up through the hole and rest it on top.
To cut blanket style insulation place the product over a piece of plywood with its paper or foil side down.
Lay a two by four on top temporarily compressing the insulation to a manageable.
To build a catwalk you would usually elevate a section of the framing perhaps with 2x6s installed at 90 degrees to the joists and you would install osb or plywood on top of the elevated framing.
While wearing dust mask and gloves carry r 38 batts of unfaced fiberglass insulation into the attic.
There are two ways to insulate triangular attics behind kneewalls.