I think the only emoticons available are the ones in the instant messenger apps. Other than that I'm not sure. You may can do a google search and find 3rd party smileys that may be able to be added to messages.
I searched around for emotions, too, but was unable to find answers I liked. In using YIM, I can do some of the normal yahoo emotions (as long as I know the keys to press :P), but nothing for text and mms messages.