By doing nothing, except maybe configuring your PDC Emulator to sync with an external source.
DCs will sync with the PDCe, members will sync with the DC authenticating them--BY DEFAULT.
So all you need to do is open a command prompt and configure your PDCe to use a more reliable ntp server than time.windows.com:
w32tm /config /manualpeerlist:1.2.3.4,0x
8 /syncfromflags:MANUAL /update
w32tm /resync
Replace 1.2.3.4 with a time server geographically near you (see list below), and make sure that UDP port 123 outbound is allowed in the firewall.
A list of the Simple Network Time Protocol (SNTP) time servers that are available on the Internet
http://support.microsoft.com/?kbid=262680Basic Operation of the Windows Time Service
http://support.microsoft.com/?kbid=224799