Where do they go?!
Open up the save you want to edit and navigate over to the "Raw" tab. Click
Player -> Appearance -> Head Morph
This is what we're interested in.
Open "Texture Parameters" by clicking the box that looks like this [...]
and a second window will open.
HAIR_Diff and HAIR_Mask is where the 2nd line goes (it ends in the suffix -Diff)
Hit okay to close the texture window, save your changes and you're done.