There are several ways to update. At a bare minimum you need a cell phone with texting capabilities. You can also use the internet or an ipod touch (which has wi-fi, u must be in range of a wi-fi source though).
There are apps for the smart phones and ipod touch.
There are several other ways to update using text such as twitter, ping, hellotxt.
Here is the big HOWEVER, to my knowledge there is no way to change your "mood" on MS using the text method. I don't use MS much anymore (FB only the last year or so), so maybe someone can confirm or rebut this. I'm not sure how you would using text.
This is why I am leaning towards her either having or having access to either an ipod touch (again, I assume this would show up as mobile, but I need to grab my daughter's now that I'm thinking about it and confirm this) or a smart phone with the app for myspace on it.
Does that help?