Alright, for future reference the name of that character sheet is "D&D 5e by Roll20". So regarding custom classes and that sheet, there is no general automation for pulling information from other websites into Roll20. However, depending on the website there may be some methods. Example: If you have a character on DnD Beyond there is Beyond Importer, an API Script that can transfer the JSON data over. Unfortunately, that doesn't sound like it will apply to your situation. With that said, I might be able to help streamline the manual method for entering the information into Roll20. Could you elaborate on what you are currently doing?