http://help.sap.com/saphelp_erp60_sp/helpdata/en/ae/101640a991c742e10000000a1550b0/content.htm
Here are the steps you need to follow (this is just one way and there are other ways):
1. Create a Simple transformation for the data that is coming in XML using tcode: XSLT_TOOL
2. Read the XML file data as you read the data for CSV file
3. Use 'Call transformation' command to convert the XML data into internal table.
Here is a simple example: http://scn.sap.com/docs/DOC-43158
You can also search for 'Simple transformation in SAP' for more insights.
-Chandra