Here is a cleaned-up version of the script from the post to which you linked:
Option Explicit
Const xlXMLSpreadsheet = 46
Const xlCSV = 6
Dim xl, wb, ws
Dim args : Set args = WScript.Arguments
If args.Count <> 1 Then
WScript.Echo "Syntax: cscript " & WScript.ScriptName & " filename"
WScript.Quit(1)
End If
Set xl = CreateObject("Excel.Application")
Set wb = xl.Workbooks.Open(args(0))
xl.DisplayAlerts = False
For Each ws In wb.Worksheets
ws.activate
wb.SaveAs CreateObject("Scripting.FileSystemObject").GetBaseName(args(0)) _
& "_" & Replace(ws.Name, " ", "_") & ".csv", xlCSV
Next
xl.DisplayAlerts = True
wb.Close False
xl.Quit
WScript.Quit
It should do what you want. You call it like this from a command prompt:
cscript SCRIPT.vbs INPUT.xls
It creates output files INPUT_SHEETNAME.csv
.