cvs export of ChangeLog for ONLY the last 'n' days

[David A. Desrosiers]

I'm trying to do a cvs export of a ChangeLog for a very very busy
project, but I ONLY want the last 'n' days/months of the log itself.
>From what I've been reading/trying (Coroilis book and Cederqvist), it
seems as though I can only go from a previous date until the beginning of
time. I'd like to get a snapshot of the last 'n' days/weeks/months of
activity in the cvs. How do I do this with cvs? I'm puzzled. 

Yes, I could do an export of the whole ChangeLog (very very large) and
then with perl, try to chop off the first 90% of the log, but that's
inefficient. 

Any ideas?