hmm not sure i understood your question here but will try to be of some help,
if you have the admin user/pass then you can use a tool such as dameware
utilities it is true, but with a graphical interface if the admin is in front of his
computer (guess who saw that

) he will see everything you do, if i was in
your situation i'd do the following:
First connect with dameware with the admin account, then opening a console
MSDos system the create a user(with admin right) using appropriate net
commands, tehn do your things that way, if by any luck Terminal service
is installed then you could use the computer remotely as if it was really yours
even the system administrator can't see it.
But be carefull there are possibilities to see who's connected and opened a
session so that tracing you would be very easy... hmm who sais double remote ??
Hope it helps a bit ^^