No problem
I have a tutorial
here but that's more for installing new markings without replacing any.
It's very simple. Drag all the images into your Feralheart >> Media >> Textures folder. The markings.cfg file you can drag into just the Feralheart folder, make sure you replace the old one.
There is one issue though. The amount of markings in the .cfg file exceeds the overall limit and so some will not show up, there's no fix for this currently but you'll still have access to many markings.