you have to get the driver zip file, which you found from the link on the TuneEcu site, saved in a folder on your hard drive. The file contains drivers for 32 and 64 bit. Once you get to the installation stage, the system will pick the correct driver from the folder you saved and unzipped the drivers from.
Then you have to disconnect from the Internet. When you plug in the cable, I assume Windows 8 will automatically load a driver, probably the wrong one.
I only used Win 8 for a week or so before trading the desktop for a Windows 7 machine. So you have to switch out of the app view to the traditional desk top view. Then you need to figure out how to access the device manager to properly install the drivers. The instructions for doing this are on the TuneECU site. They are very explicit, done by me and Tom Hamburg. You have to update the driver in the com/lpt device and again in the usb controller device because it's a usb cable but it's being accessed by the program through virtual com port.