there is no dedicated GUI for such feature but it's possible.
In case of RealVNC/TightVNC, that use registry to store its settings, you can run the VNC Deployment Wizard and select "Upload custom Windows Registry entries" task.
Then you will need to add registry values that you want to deploy to a remote computer and finish the Wizard.
The server will needs to be restarted to pick-up the new settings. This can be done via VNC Manager's Service Manager or Restart VNC Server management tools.
In case of UltraVNC server it gets a bit trickier. You would need to update ultravnc.ini file. I don't think there is a way to edit individual entries, I can only think about replacing the whole ultravnc.ini file.
This can be done via Remote Exec feature. New ultravnc.ini can be added as a "Support file" to a remote tool settings. You can execute sc.exe as the remote tool. This way you kill two birds with one short, replace ultravnc.ini and restart UltraVNC server with sc.exe.
Kindest Regards,SmartCode Solutions Support