This is just Earthbind's mod, "Lucy West Companion" ported to work with TTW. All credit goes to him for the original work to make Lucy West a team member / follower.
Mostly, this is just a basic conversion, and then modification of a few scripts to disable FNV's automatic companion wheel. Earthbind went through all of the hard work, making Lucy West a fully voiced as a companion, etc.
For instructions on how to get Lucy as a follower, go to the Nexus page. I have tested this conversion and it works fine.
If you like this mod, please download and endorse the original.
THIS MOD SHOULD BE VIEWED AS A "DEMO" - THERE ARE STILL SOME ISSUES - particularly, Lucy doesn't seem to like to be fired.