I just went from v2.1.0.2 client to v2.1.0.4 on my workstation last Thursday and
now the scripts that I execute to monitor daily events are all breaking because
of this change in the date format, from 4 digit year to 2 digit year.

This is really not an acceptable method of change. Firstly, going from 4 digit 
to
2 digit year is going backwards. Secondly, irregardless of whatever standards
ADSM is trying to follow, provide the change as an option rather than the 
default.
The 4 digit year has been around since day one and the developers should realize
that there are people like me who have coded scripts based on that format. 
Lastly,
there should have been some or better advanced warning on this.

Having said all that, the question still remains: How do I change the 'locale'
to go back to 4 digit year?