This Driver doesnt get installed easily in Windows 8.1 .. Try the method given in
Browse to the blog's VCOM driver post to see more...
This thing really has helped many people with their issues with VCOM in Windows 8.1! Hope this helps you...
Try the method given in link .. To disable Signature Verification for drivers do this :
Press Win + C button to open the charms bar.
Click Change PC Settings
Click Recovery in left hand side
Below Advanced Startup click restart now.
The PC will now show a blue screen with some options. Click Troubleshoot.
Then Advanced Options.
Then Startup Settings.
Then click Restart.
Now PC will restart and now it will show some options.
Click 7 to disable Driver Signature Verification. And now PC will boot into Windows.
Share this if you find it helpful!