The Tableau workbook is in a shared drive that we both have access to. If I export the packaged workbook to the shared drive, will that do anything? It just won't let him connect to the excel documents I created.
OK, so at packaged workbook (twbx) is actually a zip file. You can open it with any zip utility. Tableau collects all the files it needs to recreate your visualization, creates a file structure, and zips this all up into the Package workbook. In the case of flat files (Excel, etc.) Tableau makes a copy of your Excel file and includes that in the Zip file. So at this point if you make changes to the original Excel file, these changes won't be reflected in the packaged workbook because it is looking at a copy of the file not the original.
But this probably doesn’t resolve your issue.
When you say ‘he needs to modify one of the sheets’, is this one of the Excel sheets, or one of the Tableau sheets. When you say ‘It won’t let him connect to the Excel file’ are you saying he is getting an error (what does the error say) or is he not able to see the file on the drive?
If you can explain a bit about what is happening when he tries to connect to your workbook, then we can probably sort this out.
Not sure but I think you need set up the unc path if the excel file is on shared drive too: