I figured this out via a script called LTICopyScripts.wsf which is run by the task CopyScripts in the default task sequence, certain scripts are copied to the location C:/Minint - which is removed at some point during the imaging process. So if you modify LTICopyScripts.wsf to include your own files they will also be copied across and you can run things from this folder before it is removed.
Also I was doing something stupid, scripts can be run directly from the network share without having provide additional permissions - those permissions are already provided some how via the imaging process.
cheers
Dan