Looks like you can get a 1998 version of the clock at http://ftp.twaren.net/OpenBSD/distfiles/?C=N;O=D by ctrl-f-ing 'dali'. Still poking around to find the magic, though.

Edit: Based on the version file inside the package marked 1998 in that index, it was last modified at the very end of 1997, so it won't contain the prank code if jwz's dates are right. The one immediately above it, however, despite being listed as a 2001 release, has a modification date of November, 1999.