Scale total height phylogenetic tree

Question

[gubrins]

Heys,

I calculated several trees for different parts of the genome for the same labels (tips) and I would like to plot it as here:

I don't mind the mitochondrial tree, what I would like to do is to plot in darker black the consensus tree and more blurred all the other trees that I calculated to get the consensus tree. I tried the densiTree function from phangorn in R, but the results are not visually nice. In the paper where I obtained this image they mentioned that they "Branch lengths were scaled for visualization so that the total height of each tree is the same." So, how I could scale the branch length? If not, do you know any other way to plot a similar thing to this one? I would be extremely grateful!

Thanks in advance!