Password changing prompt.

I need to be able to change a password on a windows 2000 domain without the window 2000 client actually being part of the domain.

I have several clients that need access to domain shares but the desktops are not attached to the domain. This I have solved. However when it comes time to change their password they cannot. I tried using the
net user username * /domain
in a script but the PC has to actually be attached to the domain. Any ideas?