Vicidial has only been integrated with one version of vTiger: 5.1. but the integration has not been maintained for quite some time. it may stilll work, but ... I would advise an install in a Virtual system for testing purposes to see how it all fits together before making any modifications to your live system. Virtual will only work for one phone call with Vicidial, but that's perfect for testing.
the install process would be on the vTiger site to install vTiger in a Vicibox server.
However, I highly recommend you look at installing a later version of vTiger (5.1 is buggy) and re-integrating it to suit your direct needs or (better yet) install SugarCRM and integrate that based on your needs.
If you install Vicidial with GoAutoDial, the installation process is a little less involved, but then you'll have an older version of Vicidial unless you upgrade.