Is it possible to integrate a D3js visualization as a panel in dashboard through source editing? If yes, how do I do that?
If you're talking about the default .../app/search page, no - there's no reasonable way of changing that without major headaches.
It's a bunch of .js files stored in $SPLUNK_HOME/share/splunk/search_mrsparkle/exposed/js
, I've done some changes myself for showcases - so yeah, it is possible.
However, any changes made there will certainly not survive an upgrade and won't make any friends in support.
Instead, have you considered using SplunkJS/Webframework to build your own search page? That would live in your local space, survive upgrades, and not mess with built-in features. Here's a pointer on where you might get started: http://dev.splunk.com/view/SP-CAAAET9
If I am willing to stock up on aspirin and bear with the headache, would you know if it is actually possible?