To apply currency formatting to a specific range of cells in "C:\ExcelFiles\Summary.XLS" the following syntax would be used:
ConvertXLS.EXE /S"C:\ExcelFiles\Summary.XLS" /T"C:\ExcelFiles\Summary.XLS" /P108 /1"Sheet1" /2 A19:F19 /3 $#,##0.00 /4 3
The /S and /T switches specify input and output workbook respectively, which in this case is the same workbook. You can optionally keep the input file unchanged by specifying a different name or path for the output file.