Is it possible to run a build step with admin rights ?

i need to run an installation script through an admin command line. is it possible to do so? if not, is there any way i can work arround it ? i tried 'runas /user:Administrator' but due to how my environement is set up the admin doesn't have a password assigned to it, and windows doesn't seem to like that very much (i'm running a WIN 7 64bit). i also tried to work arround it by creating a shortcut to the script in question and checking 'run as administrator' in properties>compatibility, yet that wasn't available as it was greyed out.