Общие вопросы

http://msdn.microsoft.com/library/default.asp?url=/workshop/author/dhtml/reference/methods/execCommand.asp
http://msdn.microsoft.com/library/default.asp?url=/workshop/author/dhtml/reference/properties/contenteditable.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnmshtml/html/createwp.asp

ну и для мозилки (1.3):
http://xopus.org/index.jsp?menu=downloads

ю велкам:)