More info: http://help.transifex.com/features/client/index.html

1) To initialize a new project on Transifex:

# tx init
# tx set --auto-local -r hexchat.main "po\<lang>.po" --source-lang en --source-file po\hexchat.pot --execute

Append 'type = PO' to .tx\config without apostrophes

Push the resources to Transifex
# tx push --source --translation



2) To update online translations:

Regenerate the source file (hexchat.pot) on a Unix machine
# rm po/hexchat.pot && ./autogen.sh && ./configure --enable-nls && make

Push the updated source file to Transifex (this automatically updates all translation files)
# tx push --source



3) To update repo with online translations:

Update local copy with Transifex updates
# tx pull

Update GitHub repo
# git add po/
# git commit
# git push



4) To update just one translation with local changes:

# tx push --translation --language xy

Where xy is the language code



5) To force updating translations:

# tx pull --force

This might be required when the repo is freshly cloned and thus timestamps are newer than on Transifex.