Stu,
I suggest entering "me" in some unused field and then reference it in your other fields with Code Replacement. On your first pass, you enter your codes corresponding to what is in the photo. Then apply an IPTC Stationery Pad to all of your images, using \{field_variable_name}\ in your Description and Headline, and \{field_variable_name}1\ in your Keywords field. You can easily fill out all of your IPTC data in two passes: the first pass identifies the subject, and the second pass fills in all of the specific data.
HTH,
-Kirk
BTW, Code Replacement is incapable of replacing data in more than one field when used interactively (like in the IPTC Info) but is very capable of replacing in multiple fields when used in batch mode (IPTC Stationery Pad.)