Large file conversion

Has anyone out there had to deal with a large file conversion, i.e., the data to be loaded into R/3 is very large, too large to fit in an Excel file. Originally we suggested to the conversion team to put their data in an Excel file and we would flag all the records that were not loaded so they could find them easily and correct the data. However, now they tell us the number of records is too large for an Excel file and they DON'T want to split the file up into manageable pieces.

They also don't want to use a BDC session to correct the errors.

Any sharing of past experiences would be appreciated.

Thanks.

Nic