The PDF contains the description of the functions of the last released version of the FGULINK.DLL. This version is available from Velleman web site.
For the test version of the FGULINK you can find some instructions in this thread:
The driver from Velleman site is the original one and is OK for the FGULINK.DLL test version too.
If your PCGU1000 generator works OK with then PcLab2000SE there is no need to update the driver.
You can download the latest FGULINK beta test version from this link: vel255.diinoweb.com/files/FGULink_update_4.zip
I think you have to copy all the four files of the package to a folder where Labview has access to (but not to Windows\System32 folder).
You may first test the package by running the FGULink_Demo.exe in this folder.
If you are using Vista then you have to select “Run as Administrator”