Uploading values from PC to a WebReport Selection Screen Field

Hi I have a requirement and wondering if it is possible to implement.

Running any R/3 Report or Query in Excel pops up the selection screen and we can upload mutiple values from PC file to a selection field.

This option(uploading values from file) is not available for web report.

Any Idea how can I achieve.

(I have tried to use one of the unsued characteristics variable to enter the file name, and using user exit upload the data into the variable in question, but this is not working)

Thanks

Ravi