samba - Oct 2008 - logging user login and logout time on Samba 3 DC

Hi,

I have a Samba Server running on FreeBSD.
I need to track the time in which the client machines are used by
people to login to the domain
I also need to track the time they log of.

How can this be done?
Can Samba be made to log these details to config files on a per host basis?

Thanks and Regards

Siju