Install Mercurial using the virtualenv tool that is outlined in the Installing Django documentation, but replacing "django" with "mercurial". It is recommended that you create a separate instance/virtual host for running a mercurial server to isolate the environment.
Once installed you'll need to create a ".wsgi" script that looks something like:
...
When you need to sync the change back do the same steps of first going to "/davportal/".
Creating push back to Mercurial server.
Confirmation showing the use of "/davportal/".
Checking back in the web interface you can verify that the change has been committed.
You can also request that kproxy be enabled for your Mercurial server.