For some additional examples of handling multiple sheets, see the QV Cookbook example "Load multiple sheets from Excel workbook". You can download the WV Cookbook from http://robwunderlich.com/Download.html.
The example deals with a single xls file. If you want to process all xls file in a directory, an interesting alternative to using filelist is using the Excel driver as discussed in the "Notes" tab in the script. The filename (minus the .xls extension) will be in the SQLTABLES TABLE_CATALOG field.
The methods of getting Excel tab names using an OLE or MSDASQL connection and "SQLTables" to list tab names works OK with QlikView but fails when a reload is carried out using QVServer9 (64bit). This is because there is no 64bit OLEDB provider for Jet. Has anyone found an alternative way to determine tab names from excel?