I just remembered about posting my program.
So here goes.
Just unzip the contents of the folder to wherever you want. When the program is run it will poll the gps receiver for the correct date and time, and then set your pc date and time accordingly. It then exits.
It's completely automated and headless. So you wont see anything run. Check the gpstime.log txt file in the programs directory to find out if it worked.
You can add this as a startup/resume command in centrafuse.
You cant read data from the gps when it's in-use by centrafuse. So you must use something like xport to split the com port into two.
Then set centrafuse to use one of the new virtual ports and then gpstime to use the other.
You can set the port number by editing settings.dat in the programs directory. It's the first number before the comma. If your baud rate is not 9600 then you will need to change that too.
Download gpstime
here
Download xport
here
This was designed with the infill g4 in mind. But anyone with a receiver set to NMEA mode should be able to use it.