This is ideal for a custom search command in which you can manipulate the data and insert knowledge dynamically. This, however, needs to be done in Python and will require you to follow the rules of integration documented here.
Please see the example in the link provided. In the end, however, it should look something like this:
results = splunk.Intersplunk.readResults(None, None, True)
for event in results:
""" data analysis and calculations here """
""" add new field 'newname' """
event['newname'] = "".join(newval)
I hope this helps.