xp_cmdshell exec permission for non-sysadmin user

(1) Enable the xp_cmdshell procedure
Enable xp_cmdshell by using sp_configure or "Surface Area Configuration"
USE MASTER
GO
EXEC sp_configure 'xp_cmdshell', 1
RECONFIGURE
GO
(2) Create a login 'Domain\TestUser' for the non-sysadmin user that has public access to the master database
(3) Grant EXEC permission on the xp_cmdshell stored procedure
     GRANT EXECUTE ON xp_cmdshell TO [Domain\TestUser]
(4) Create a proxy account that xp_cmdshell will be run under using sp_xp_cmdshell_proxy_account
      EXEC sp_xp_cmdshell_proxy_account '[Domain\TestUser]','pwd'
Note: pwd means windows password for [Domain\TestUser] account id on the box.
(5).Grant control server permission to user
USE master;
GRANT CONTROL SERVER TO [Domain\TestUser]
GO