Are your users currently using two separate apps (ExpenseIt and SAP Concur Mobile)? If so, the only thing that will change in the process is that ExpenseIt will be accessed from SAP Concur Mobile, so there won't be any real change in processing card transactions. Use the ExpenseIt option in SAP Concur Mobile to take a picture of the receipt and then tell your users to wait about three days when the card transaction comes in. SAP Concur will match the ExpenseIt item to its corresponding credit card transaction. Once they have been matched, then users add it to their expense report. Now, if your users are not currently using ExpenseIt or processing card transactions, then there will be a little bit of a learning curve.
Could you provide a little more information as to what your current situation is, please?