execute xp_cmdshell and other SA storedproc

Hi all,

I have to execute stored procedures containing
xp_cmdshell and certain system storedprocedures in msdb and master
with a user who is not SA.
(i.e iam able to execute stored procedures when i log as sa,
but any other user cannot run them)

Pls tell how to do this, it is quite urgent.Books online reviews:
When xp_cmdshell is invoked by a user who is a member of the sysadmin fixed server role, xp_cmdshell will be executed under the security context in which the SQL Server service is running. When the user is not a member of the sysadmin group, xp_cmdshell will impersonate the SQL Server Agent proxy account, which is specified using xp_sqlagent_proxy_account. If the proxy account is not available, xp_cmdshell will fail. This is true only for Microsoft Windows NT 4.0 and Windows 2000. On Windows 9.x, there is no impersonation and xp_cmdshell is always executed under the security context of the Windows 9.x user who started SQL Server.

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