Well, no-one else is making a... constructive reply to this, so (even though i haven't made any plugins for a while) i will try.
If you want to change ur status, you should send back a command like /online where you would normally send back some text.
IIRC, no-one ever managed to build an auto-responder or get messenger plus to perform an action every x seconds, but if you can get one, make sure you share it with us all
You can retrieve the contact's current status using the IDispatch you're sent - i'm on my laptop at the minute, but when I get back home i'll post the wrapper class I generated for that.
P.S. You can make messenger perform a series of actions by sending back a string like: "/online#3#I'm off for a while now.#3#/away"
the 3s are the amount of seconds in between the commands (again, i'm not sure, but it's something like that).