Ritchie,
You can open xml file directly in notepad from NS machine and look for below key value pair.
<key>Target</key>
<string>/Volumes/Macintosh HD</string>
It is recommended to keep all parameters as is and just change Target as required.
For example if you are trying to install OS X on /Volumes/Install then you can change Target key value as
<key>Target</key>
<string>/Volumes/Install</string>
Also make sure that /Volumes/Install is erased before continuing with OS X install task.
Thanks