http://www.ni.com/white-paper/14311/en/
Should be possible with a Trimble thunderbolt. While I've used it for a time and frequency reference I've never pulled time off of the serial port connection. If you can pull time from the device you should be able to get pretty accurate timing using this method.
The NI USRP-2930 and NI USRP-2932 use this method with an internal GPS Disciplined Clock.