Windows NTP client - allow large time offsets

During the christmas holidays, I 'm doing my own christmas ralley to meet a rather huge family. At these visits I'm often asked to solve some smal or great PC-Problems. Even I'm no PC-pro, I'm something like the one-eyed among blindes. Ad of course it makes more sense to solve problems onsite than remote using just the telephone.
One of the problems was an old laptop with an decrepit BIOS-battery. This led to an totally insane system date at every startup. Even with a proper system time and NTP-Server setup it never set the time correctly as the time offset was to large.
After some searching within the registry I changed under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config the parameters MaxNegPhaseCorrection and MaxPosPhaseCorrection toFFFFFFFF, which is the maximum value (approx 136 years). Now at every connection, or at least at every manual time adjustment, the time is really set (and no boring error message is shown).