Inserting a single node custom SOAP Header in auto generated Proxy services.

There are millions of samples in the internet that explains how to insert a multi node SOAP Header.
What I mean is that there are plenty of examples in the internet show how to do the following:
<SOAP-ENV:Header>
< Security >
<Username>AUSER</Username>
< Password >APassword</Password>
</Security>
</SOAP-ENV:Header>

But what I want to do is ,

<SOAP-ENV:Header>
<CustomTag1>adf</ CustomTag1>
< CustomTag2>sghg</ CustomTag2>
</SOAP-ENV:Header>


As you can see the CustomTag1 and CustomTag2 are the child node of the <SOAP-ENV:Header> and not enveloped by any intermediate parent node as shown in the first example.

What I want to know is how can we insert our custom SOAP Header directly into <SOAP-ENV:Header> by editing the auto generated proxy (CS - C# file)from web services?

Note: the web services does not expose the SOAP Header information in the WSDL.