Hi ... Good question but i am not sure but i would not think you can ... If you like try asking that question on this forum which deals with messenger of all types ... Link below
I see that now, many thanks. Another question - can I be available for one contact, but 'away' to another, without letting them know I'm blocking? I hope this makes sense!
Not that I'm aware of. I simply block "all" and "unblock" the contact I wish to speak with. They are unaware of being blocked as I simply appear to be offline to them.
Move all your contacts to the "blocked list" and be sure that the box is checked above it (allow only contacts on my allowed list to view my status). Unchecking this box will allow your blocked contacts to know that they are blocked.
You'd be surprised how many of your contacts already have this in place!