Large number of characterist values to filter. Excel BEx and BEx Web

Hi, I have an Excel BEx Workbook where the users have set up a Customer Payer Filter with 75 Customers. They are able to add to add or remove entries to this workbook and just save the workbook for next run.

Now I am converting this workbook/query to the Web and trying to figure out how I am to give them the same functionality in BEx Web? Anyone know how I would accomplish this?