ANSWER:

thanks patrix, that did it on my ML 10.8 machine. i was working remote on a mac and the screen saver kicked in, and all i have is the password box. used to be able to put in admin username/pwd but not anymore, i think it changed in 10.7(?)

I was able to ssh and use admin creds to sudo pwd change and then use ARD to unlock screen. thanks again!

micheal from http://apple.stackexchange.com/questions/92243