admin rights

I have created a powershell script that includes get-item with a destination of the users "C" drive.  Due to lack of permissions on the users desktops and directories, I was wondering if there is a way to do an equivelent runas command during the file copy.  I have tried using a dos batch file with the runas command but I get prompted for a password.  Any help would be greatly appreciated.  Thanks.

Off the cuff, my response is: You could map the destination directory to a free drive letter using alternate credentials, perform the copy, and finally tear down the mapped drive. 
 
It sounds like this is a script that will be run at user logon under the users credentials, yes?  Is there any way to move this process off the workstations onto a server where it can be run under admin credentials?