See description page and please note that the FormlistID's in the example script are not correct.
Backshield3PModShieldList ID is: 0x0000083C and Backshield3PModBackshieldList ID is: 0x0000083B

A copy of Neovalen's tutorial for making Shield Meshes for Dual Sheath Redux by Neovalen (original link: https://www.nexusmods.com/skyrim/mods/34155)

bsa version (includes meshes optimized for SSE)

loose files version

Archived file version with .esp

Archived file version with .esl (main is not required)

This patch will fix the Dragonbone Shield. Thanks and all credits to Longerfield.

loose files (meshes only) in case you use the bsa version and want to adjust the backshields position