I would make a csv file that has a column for tagpaths and a column with the notes data, if you already have that in your excel spreadsheet. you could then import that into a table in your database and use a script to write to the notes section of each tag that you have in your list.
here is an example of writing to the notes part of a tag.
note = "test"
system.tag.write('03301/CommStatus.AlertNotes',note)
If you need more help let me know.