Do you have to generate the data in a Report? Could you use Advanced Find to get at the data instead? If so, then Advanced Find has the ability to export to a dynamic excel sheet that updates automatically. You can then create your pivot table from there.
Another option if you are comfortable with DSNs and sql is to create an sql script that assembles the data for you and then use the External Data/MS Query type functionality in Excel to pull the data in. You can even do this as the source for your pivot table without going to tabular data first.