Creating power users in Active Directory

I have seen this question posted numerous times on numerous boards, but still no real answer. There are suggestions for how to this or that, but no real answer.

Does anyone have a straight answer to the question?

What do I have to do to an AD user account to give that user Local Machine “poweruser” privilege permission, no matter what machine they log in on. I have numberous users with moderate attrition that must have power user permission to run applications on computers. They move from site to site, using different computers at each site. I am a one man show and going to each site to build each new/leaving user into and out of each machine is stagering to think about.