Selective Time Machine copy
ditto didn't cut it, but rsync did.  It has a --link-dest option, that uses files in that folder as the base to link to for duplicates.  It's important that the source path for rsync end in /.

To prepare, in the location I'm going to store my copy, I create a symlink to the 1st archived folder I want to copy: ln -s -h -f /Volumes/MyBook\ 2/Backups.backupdb/Mini/2012-08-02-003832/Macintosh\ HD/Users/jerrybarrington/pathtothefolder/ /Volumes/MyBook\ /Volumes/MyBook\ 2/CK2.backup/Last.

Then to copy: sudo rsync -a --delete --link-dest=/Volumes/MyBook\ 2/CK2.backup/Last/ /Volumes/MyBook\ 2/Backups.backupdb/Mini/2012-08-02-003832/Macintosh\ HD/Users/jerrybarrington/pathtothefolder/ /Volumes/MyBook\ 2/CK2.backup/2012-08-02-003832/.

Lastly, update the symlink to point to the new copy: ln -s -h -f /Volumes/MyBook\ 2/CK2.backup/2012-08-02-003832/ /Volumes/MyBook\ 2/CK2.backup/Last.

For each subsequent copy, repeat step 2, changing both instances of 2012-08-02-003832 to the next date I want, and then repeat step 3.

see http://www.mikerubel.org/computers/rsync_snapshots/ for my inspiration.