The latest versions of Tailor and Mercurial don't play well together (as of 2007-11-19), so you can't automatically import from Mercurial to darcs; see the gory details, noting that the suggested workaround of using an old version of Mercurial doesn't work because then it mismatches with the repo format.
Once you start to use darcs instead of Mercurial though (I found that darcs get --partial was reason enough), you might find the following commands useful:
hg add -> darcs add -r *
hg archive -> darcs dist
hg ci -> darcs record -am 'Something.'
hg status -> darcs whatsnew -ls
hg diff -> darcs whatsnew -u
hg archive -t tbz2 -> darcs dist && gunzip ... && bzip2 ...
You can also abbreviate them, e.g. darcs w for darcs whatsnew.