PEP will paste the pastetext exactly as entered. You can put separate lines in the pastetext by simply hitting the return key.
The interpretation of the newlines is determined by the field you are pasting into. If, for example, you are pasting into an HTML field then you would want to put the characters "<br/>" in the pastetext wherever you wanted a line break.
You could use "\n" but if the field you are pasting into doesn't interpret that as a newline, it will just display the characters literally.