Create mass activity upload

Hi

I have an external list (excel spreadsheet) of customers that we have sent a specific letter to. Is it possible for me to pull the customer numbers from this spreadsheet, and then have CRM create a business activity for each of these customers. The activity itself will be generic, with the same categories and text for each activity. I would like to be able to do this as a mass upload if possible. I have found the tx CRMD_MKT_PROC however I have not been able to assign the spreadsheet values via this transaction - it works from info sets.

Does anyone have an idea on how I could achieve this? At present, the marketing part of CRM has not been utilised at all so I do not yet know my way around this part.

Many thanks

Cara