Hello,
Sure, here are the pulling settings I used. I tried with a few different settings and got this one based on insights from a response to a previous post of mine.
pull = yes
pull-ngroups = 2
pull-group1-name = Left
pull-group2-name = Right
pull-ncoords = 1
pull-coord1-type = constant-force
pull-coord1-geometry = direction-periodic
pull_coord1_vec = -1 0 0
pull_coord1_k = 100
pull-coord1-groups = 1 2