You might take a look at Dave Roths Adminmisc module www.roth.net

It has a nice little command that you can use:

Win32::NetAdmin::UserChangePassword( ($machine | $domain),$user, $oldPassword, $newpassword)

or better yet

Win32::NetAdmin::SetPassword( ($machine | $domain),$user, $newpassword)

The domains in question will have to grant you an access to do that. They can set up a global account and give you the authority. You can't side-step the security if you think about it. Microsoft has its problems but that would be a HUGE one if you could do that! ;-)