I'm planning this feature for Project RP, which will be a proxy for Messenger.
I can't see how this can work as a plugin, but then again, threading could be used.
In fact, that's probably the best way to do it. Pseudocode:
code:
In Uninitialize():
Create thread on custom function
In your own function (call it what ever you want):
Sleep for x seconds
Use the IMessenger3 pointer to start a sign-in