Facebook- I wanna turn off chat but only chat with some people?

[titon]

there is a option on facebook to turn off your chat for some selected people which is called as black list.
but there is no option for white list where you can select some people, only they can see you and rest of the friend cannot.

if your matter is for one or two friend then you can do one think.
turn off your chat for all friend i mean which is the general option then send message to those friend.
if they are online you can talk as a chat.
thats a simple way.