I'm not sure if there is one but I'll make a quick one since I've made the Squidward skin and Zoidberg skin. You first have to navigate to the skins in your game folder which is normally something like "C:\Program Files\Steam\SteamApps\common\Octodad Dadliest Catch\Content\Models\Characters" Next you need to pick the skins you wish to replace. For Octodad it is the Octodad, OctodadExposed, OctodadUndershirt, OctodadWedding, and Octopus dds files. Some editors may have native DDS file support.

I had to use GIMP which is a free open source picture editor and get the .dds file plugin which allowed me to open and edit the files. I did a colorize option on sections outline in the skin and changed the RGB values until I got a desired effect. Next you just need to create a workshop file and upload it. Unfortunately due to the nature of the game currently skins do not persist which means that if you install a workshop skin addon that is not in a level it wont be applied to the game forcing a manual installion. To install the skin just overwrite the files that you changed.

You are free to use my Squidward or Zoidberg skins and workshop files to get an idea how it works, or just edit the files and change them to whatever you wish. Also note that you cannot change or add things with a simple reskin that would require changing the model itself (which some others have done)

Link to my squidward skin for reference if you need it http://steamcommunity.com/sharedfiles/filedetails/?id=229768702

Feel free to shoot me a message if you have any other question I can try to answer!