Specifying namespace prefix on WebMethod

[supercodepoet]

What I have is a .NET 2.0 C# web service for quoting a tax rate. The
current response wrapped in the SOAP envelope and body is :

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<GetTaxRateResponse xmlns="http://services.leggett.com/lpcs/tax/">
<GetTaxRateResult>
<StateName>MO</StateName>
<Rate>.0695</Rate>
</GetTaxRateResult>
</GetTaxRateResponse>
</soap:Body>
</soap:Envelope>

I need to be able to search this document with XPATH with the libxml2 C
library in a C program. The problem is that I am not able to pickup the
Rate element with the XPATH expression "//Rate". libxml2 is not able to
find it because you can not register a namespace without a prefix. Is
there anyway I can get my .NET web service add a prefix to my WebMethod
namespace?

Thanks,
Travis