Create a intermediate entity with an association to a parent (may be your imported ExcelFileDocument) and Columns: FieldName, RowNumber, Data1, Data2, etc
Import the excel with the Excel Importer from the market place, (Create a template, just follow the procedure, set association to parent) be sure to fill the rownumber.
After excel has imported Loop thru the read data (retrieve over association from parent) on order of rownumber, compare the field name ('Item No', 'DPAS', etc) and process per line and fieldname.