I was doing bit of R&D around implementing, writing custom multilist with search while doing my bit of research I understand sitecore has not unified the multilist with search in a way so that it can be used widely to solve problem for content author. May be there is less documentation out there where developer ends up writing custom implementation which can very well handled using right query.
Below I tried to sum up by putting some of the cool links a kind of reference to begin with.
Cheat Sheat X-path, Sitecore Query and Fast Queryhttp://www.cheatography.com/brij-baroda/cheat-sheets/sitecore-field-source-as-xpath-query-or-fastquery/
Simple problem solved
By Raul- Nice explanation
Query Bug
StartSearchLocation={110D559F-DEA5-42EA-9C1C-8A5DF7E70EF9}&TemplateFilter={5E840804-D12E-4D1F-A30F-C1A71F32F63C}
http://www.sitecore.net/learn/blogs/technical-blogs/sitecore-7-development-team/posts/2013/10/using-the-new-sitecore-7-field-types.aspx
Customize Multilist with search
https://himadritechblog.wordpress.com/2015/03/15/dynamic-multilist-with-search/
http://sitecorenj.blogspot.com.au/2015/11/multilist-with-search-querying-bug.html
StartSearchLocation=query:..&Filter=_latestVersion:*|-_templatename:Saved Query
By Fish Tank
http://getfishtank.ca/blog/using-item-field-as-a-data-source-in-sitecore
Add Selected Item at top in the multilisthttp://www.bugdebugzone.com/2015/07/add-selected-item-in-multilist-at-top.html
http://sitecorefun.baziret.com/2014/08/sitecore-tags-and-multi-site-in-action/