The Cheater's Guide to Managing Tags at LiveJournal

How to add Mass Amounts of Tags at Once

1. Copy the list of tags (separated by manual line breaks/paragraph breaks -- that is, they're on separate lines, NOT numbered or bulletted) into Microsoft Word (similar programs may also be able to do this, but I'm not sure).
2. Highlight the entire list and go to Edit, Find/Replace.
3. In the Find What: field, click on the Special button at the very bottom of the dialogue box.
4. Select Manual Line Break or Paragraph Mark. In the Replace With field, type in a comma followed by a space.
5. Then hit Replace All. Your list should now be like this: theme 1, theme 2, theme 3, etc.