MTOM Encoding and Custom binding

How do I configure custom binding and MTOM encoding? I have a custom binding like given below,

 <customBinding>
        <binding name="stsBinding">
          <security authenticationMode="UserNameOverTransport" 
                    requireDerivedKeys="false"
                    keyEntropyMode="ServerEntropy" 
                    requireSecurityContextCancellation="false"
                    requireSignatureConfirmation="false">
          </security>
          <httpsTransport />
        </binding>
      </customBinding>

And my MTOM binding is like below,

 <basicHttpBinding>
    <binding name="HttpStreaming"
             maxReceivedMessageSize="2147483647"
             messageEncoding="Mtom"
             transferMode="Streamed"/>
  </basicHttpBinding>   

How do I combine this?

You have to add message encoding element:

  <customBinding> 
    <binding name="stsBinding"> 
      <security authenticationMode="UserNameOverTransport"  
                requireDerivedKeys="false" 
                keyEntropyMode="ServerEntropy"  
                requireSecurityContextCancellation="false" 
                requireSignatureConfirmation="false"> 
      </security> 
      <mtomMessageEncoding />
      <httpsTransport /> 
    </binding> 
  </customBinding>