You could brute force it too, though not recommended
I've used this for stand alone machines.

Code:
Function SetTimeServer($Peers,$Pos,$Neg,$Poll)
  Dim $Key,$Set,$Admin
  $Admin=IIf(InGroup(@WKSTA+'\'+SidToName('S-1-5-32-544'))-1+@INWIN=1,1,0)
  ;If user does not have Admin rights then quit.
  If Not $Admin Exit 5 EndIf
  $Key='HKLM\SYSTEM\CurrentControlSet\Services\W32Time\'
  $Set=WriteValue($Key+'Parameters','Type','NTP',REG_SZ)
  $Set=WriteValue($Key+'Config','AnnounceFlags',5,REG_DWORD)
  $Set=WriteValue($Key+'TimeProviders\NtpClient','SpecialPollInterval',$Poll,REG_DWORD)
  $Set=WriteValue($Key+'TimeProviders\NtpServer','Enabled',1,REG_DWORD)
  $Set=WriteValue($Key+'Parameters','NtpServer',$Peers,REG_SZ)
  $Set=WriteValue($Key+'Config','MaxPosPhaseCorrection',$Pos,REG_DWORD)
  $Set=WriteValue($Key+'Config','MaxNegPhaseCorrection',$Neg,REG_DWORD)
  SHELL '%comspec% /e:1024 /c  net stop w32time >NUL 2>NUL'
  SHELL '%comspec% /e:1024 /c  net start w32time >NUL 2>NUL'
  ;The w32tm command does not appear to set the errorlevel.
  ;You will have to check it against another source to confirm success
  SHELL '%comspec% /e:1024 /c w32tm /resync /rediscover >NUL 2>NUL'
EndFunction