I have no idea what ICP20.exe is but if you want to use IVI, you would also download the IVI driver for the 3634
here. It should work but if there are problems, you will not be able to modify the actual instrument driver. A LabVIEW IVI driver is a wrapper that use the Call Library Node into the actual driver which is a dll written in LabWindows/CVI. There is a native LabVIEW driver for the 3631/3632 that you could try as well. It might not work perfectly but you'd have the LabVIEW code that you could modify.