Rather than change the password, I can think of 2 options that can work better and probably a lot easier. I would choose option 2 of security and to keep it more MS/AD oriented rather than adding more applications.
1. You could just remote desktop in using VNC or the alike. To make it more secure, set the service to manual, remote manage to the machine, turn it on, do what you need to do, then disable the service. That way its there and installed, but an admin has to manually start the service for it to work.
2. I remember using a feature of MSTSC/RDP where you can view and control a screen while having the target user still logged in. This is great if you want them to reproduce a problem they are having without leaving your desk OR to do something as someone else like you are talking about. Somewhere in the Group Policy's in AD there is a check box to allow remote users in a specific goup to view or view & control a session. I know I used it on a box set up for TS clients to connect to, but I am almost sure that there is a way to do this on normal desktop boxes.
I will google for the how to page that I used a few years back and report back if/when I find it. If anyone else knows finds its first, please post it up.
-ArXiX
EDIT:
Found something about it here:
http://www.msterminalservices.org/articles...oup-Policy.html
Most of the way down, search for "Set rules for remote control of Terminal Services user sessions" also known as Shadow sessions. I think this might still work even if its not on a TS box. If it doesn't, install Ultra VNC and call it a win.
