Okay, I give up.  I'm stupid.

I've got a CF card (40MB) which has, unaccountably, decided that it needs to
have 16kB blocks.  So, I want to reformat it.

1.  I can't figure out a way to specify blocksize for newfs_msdos.
2.  Even if I could, I can't seem to format the card, possibly because there's
no real disklabel.

So, how do I label the CF card?  'disklabel -e' complains that it can't
write to the label until I create one with 'disklabel -r'.  I can't seem to
get that to work.  'disklabel -r' shows, indeed, that none is present.
'disklabel -i -r' fails, because there's no disk label.

?

-s