in reply to export excelsheet as .csv

If Spreadsheet::ParseExcel (or XLSPerl for a complete, premade solution) is not your thing, maybe ExcelPerl by strat shows you the techniques how to use Win32::OLE to do what you want.

A technique I've found very convenient is to use the Excel Macro Recorder to create Visual Basic code for what I want to do and then to translate that VB code to Perl.