Allowing Write Access Without Using IUSR

Is there any other way to write files to a directory than allowing the
IUSR write access. We have a website that will be writing XML files and
Label files to a directory outside of our website directory but I am
hesitant to give the generic IUSR account write access to anything and
wondered if we could asign a different account or if there was some
sort of ASP script we could use. These files will be created based on a
received XML string (used for label generation) then saved to the
server for archiving and/or recreation of the labels.