Use of client IP or X-Forwarded-For as a parameter that gets passed to a XSLT Transformation

[#1]

I have been trying to create a parameter using the X-Forwaded-For entry and pass that parameter to a XSLT transformation to be used as a part of the payload going to the back end service. Below is my assign message. So far I have had no luck getting this set that I know of. In the long run I would like it to be more generic so that it can be used for multiple XSLT transformations.

<AssignMessage async="false" continueOnError="false" enabled="true" name="AM-1"> 
  <DisplayName>AM-1</DisplayName> 
  <XSL name="SubscriberInquiry"> 
    <DisplayName>Set-ClientIp</DisplayName> 
    <FaultRules/> 
    <Properties/> 
    <OutputVariable>request.content</OutputVariable> 
    <Parameters ignoreUnresolvedVariables="false"> 
      <Parameter name="clientIp" ref="x-forwarded-for"/> 
    </Parameters> 
    <ResourceURL>xsl://SubscriberInquiry_req.xsl</ResourceURL> 
    <Source>request</Source> 
  </XSL> 
</AssignMessage>