Using the vania_fit skin as a starting point I have this now working as I want it on my site (http://www.ccolife.org/w/). I wanted to change the modified skin into a custom skin so that nothing gets overwritten with updates but I keep getting an error when trying to upload a zip file.
I have changed the folder name and all references in the files to vania_fit and ls_van_fit in order to avoid name conflict.
I get error code 6 (Uploadable zip-file is invalid: invalid archive mime-type or incorrect name of skin zip-archive.). I've tried from 3 different machines so I don't think it's a mime type error.
What folder structure should the zip file have? Currently I'm compressing the containing folder (and all included files) for the skin. Do you have an example zip file I could look at?