You can submit the wallpapers but following these instructions.
How to create wallpaper templates with Cinema 4D - Wallpaper - Nova Skin Forum
How to create wallpapers for nova skin with mine-imator - Wallpaper - Nova Skin Forum
If you have done the everything right, now you can publish the wallpaper. To quote from Cinema 4D thread on how to publish a wallpaper
###Publish it
- if the wallpaper looks good, send all of the backgroundxxx.png and layersxxx.png to to wallpapers@novaskin.me
- you can also upload the files here (.zip files please, also include your contact information in a text file), also send an e-mail with your contact information and the wallpaper name.
- include a title suggestion, your name, your contact info (like a link to your website)
- I’m planning to make a better upload system, but by now e-mail works fine.
###email: wallpapers@novaskin.me
Given that the latest wallpaper templates came out like 2 years ago, I wouldn’t expect that the recently submitted wallpapers will be available for the public anytime soon. However, the site, especially the wallpapers page, has just been updated recently, so there might be a chance. Good luck.