Installing existing project as plugin

Dear Everyone,

I have 1 opensource project im very interested in. I would like to
install this project as a plugin since it does not support a /theme
folder to override the app views, js, stylesheets, etc.
And this option won't be available since it has no priority for them.
Im to new to ruby to do this myself and working on another self made
project so i dont really have the time to going to build that feature

Would it be possible to somehow seperate views/css/js from the main
app and place this in a theme folder

Any suggestions advice on this would be very welcome
Thank you