You will need to add the following to your LOGIN.COM:
$! Python...
$!
$@python_vms:setup
$@mercurial_root:[vms]setup
The current versions are:
$ python --version
Python 2.7.6
$ hg --version
Mercurial Distributed SCM (version 2.8.1)
(see http://mercurial.selenic.com for more information)
Copyright (C) 2005-2013 Matt Mackall and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.