Here is my function library.  

After you unzip it you will see that there are two folders and a file.

The two folders are named  exsheet_init and exsheetload. You need to copy the two folders(exsheet_init, exsheetload.) into the \lib folder under your WinRunner installation directory.

The file named ExcelSheet.dll needs to be copied into \arch

Once you have done this, start WinRunner and open the tslinit script.
This can be found in the \dat folder under your WinRunner installation directory.
At the end of this script, after everything else, add the following line 

call exsheet_init();

Then save the script and restart WinRunner.
When WinRunner has restarted, then you can go into the function generator and in the category dropdown box, you will see a category called ExcelSheet.
Select this category to access the function.

Usage:
# sample winrunner script
# the following set the active sheet to "Sheet4" in the "x.xls" file 
set_excel_sheet("C:\\x.xls","Sheet4");
