If you don't have anaconda/miniconda installed, first install that.
Create a conda environment for ete.
conda create --name ete
Install software.
conda install -c etetoolkit ete3 ete_toolchain
Get some coffee, it takes a few minutes.
Activate the conda environment whenever you want to use ete3.
conda activate ete
Check it if you want.
ete3 build check
When you're done with ete3, deactivate the conda environment.
conda deactivate
Here is a script for midpointing rooting a tree.
import sys
from ete3 import Tree
intre = sys.argv[1]
tre = Tree(intre, quoted_node_names=True)
# Calculate the midpoint node
midpoint = tre.get_midpoint_outgroup()
# Set midpoint as outgroup.
tre.set_outgroup(midpoint)
print(tre.write())Save that as midpoint-root.py or whatever you like.
python midpoint-root.py my-tree.tre > my-tre.rooted.py
If python 3 isn't your default, you may need to type python3 instead.