italics= asterisk on either side of the word or phrase. bold=two asterisks on either side of the word or phrase. I don't know if you can do both bold and italicized.
I don't remember if you use an android or an iPhone. I have an android. There is an app for plurk for either. Plurka is the one I use. It works okay. run by lizards, though, same as the rest of it.