A couple thoughts come to mind:
You said you tried using a URL field to a UNC, but that didn't work. Could you create a KB article that has the attachment and then point to that? Then you wouldn't be replicating the attachment multiple times in the system.
Are all the steps that need to be performed assigned to the same user? If not, you could have tasks within the incident.
Finally, are these tasks something that could be automated to free up your staff to do other things and to avoid human error in carrying out these steps?
