Silicone spray and vice-grips / needlenose pliers.

Ideally you have 2-4 sets of small locking vice-grips.
This is my usual step by step:

1) Feed rope (thick) into encap.
2) Grease entire encap. w/ silicone spray
3) Dry fit shield into windshield opening
4) Attach vice-grips to all 4 inside corner flaps of encap.
5) Starting in the middle, pull rope to bottom corners, pass the vice grips.
6) Hook or pick out as needed.
7) Continue up both sides, past top corners.
8) Repeat the top, hook and pick out as needed
9) Should just pop right into place with a few taps.

Silicone spray is your best friend with these 1-piece peterbilts