How can Modify web.config from PowerShell

[leekirk]

How can add in web.config in section "system.serviceModel" if not exist xml sections:Before:\[code\]<system.serviceModel> <serviceHostingEnvironment aspNetCompatibilityEnabled="true" /></system.serviceModel>\[/code\]After:\[code\]<system.serviceModel> <serviceHostingEnvironment aspNetCompatibilityEnabled="true" /> <bindings> <basicHttpBinding> <binding name="ValidationServiceSoap" closeTimeout="00:01:00" openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00" allowCookies="false" bypassProxyOnLocal="false" hostNameComparisonMode="StrongWildcard" maxBufferSize="65536" maxBufferPoolSize="524288" maxReceivedMessageSize="65536" messageEncoding="Text" textEncoding="utf-8" transferMode="Buffered" useDefaultWebProxy="true"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> <security mode="Transport"> <transport clientCredentialType="Ntlm" /> <message clientCredentialType="UserName" /> </security> </binding> </basicHttpBinding> <bindings></system.serviceModel>\[/code\]