Range is a property of the worksheet.
You need to get the property passing in the string for location then set it.
Maybe this will help
Will open a blank excel sheet and put current date and time in 'A1'.
[CommandMethod("OpenExcelLateBinding")]
public void OpenExcelLateBinding()
{
Type excelType = Type.GetTypeFromProgID("Excel.Application");
object exl = Activator.CreateInstance(excelType);
object wb = exl.GetType().InvokeMember("Workbooks", BindingFlags.GetProperty, null, exl, null);
wb.GetType().InvokeMember("Add", BindingFlags.InvokeMethod, null, wb, null);
object[] param = new Object[1];
param[0] = true;
exl.GetType().InvokeMember("Visible", BindingFlags.SetProperty, null, exl, param);
object ws = exl.GetType().InvokeMember("ActiveSheet", BindingFlags.GetProperty, null, exl, null);
param[0] = "A1";
object rng = ws.GetType().InvokeMember("Range", BindingFlags.GetProperty, null, ws, param);
param[0] = DateTime.Now.ToLongTimeString();
rng.GetType().InvokeMember("Value", BindingFlags.SetProperty, null, rng, param);
}