$(WinDir)\System32\Rundll32.exe shell32.dll,OpenAs_RunDLL as suggested in http://forum.altap.cz/viewtopic.php?f=4 ... hell#p3688 does ask with which application instead of as which user (like the name suggests) to open the command shell .
runas /user:administrator cmd requires 1) to enter a password ech time and 2) to set a password for admin (which is not standard), hence it's not a comfortable solition.
My User Menu entry
Name: CMD as Admin
Command: I don't know yet

Arguments: %ComSpec% (this is where cmd.exe is located)
Directory: $(FullPath) (so it shall be called