I'm not worried about seeing the output on screen, just being able to manipulate it.
The line that the document gives me is this:
<!-- Read the output and extract some information from it -->
<gel:set asString="true" select="$runresult/SOAP-ENV:Envelope/SOAP-ENV:Body/NikuDataBus/XOGOutput/Status/@state" var="XOGoutcome"/>
As I'm concerned with doing something to the data within the resource write, I will change the select clause to:
select="$runresult/SOAP-ENV:Envelope/SOAP-ENV:Body/NikuDataBus/Resources/Resource/Calendar/Days"
Where I was going wrong was that I wasn't including the Soap nodes above, so the gel:set wasn't finding the data.