See also: Create a new preference
You simply need to use the preference smarty plugin in one of the administration panel templates (templates/admin/include_*.tpl).
{preference name=example_my_pref_name}
How to hide options with dependencies
Just add id="feature_xyz_childcontainer" where feature_xyz is the name of the parent features. So if parent feature is off...
For a radio field use id="fgal_use_db_childcontainer_1" for the first radio button, id="fgal_use_db_childcontainer_2" for the second radio button ...
<div class="adminoptionboxchild" id="feature_multilingual_childcontainer"> This text will just appear if feature_multilingual is activated </div>
To have a longer preference name in search results, yet a shorter one visible in the template:
{preference name=some_name label="{tr}Shorter Name{/tr}"}
Preference always visible
{preference name=feature_wiki visible="always"}
This can be useful to avoid the basic/advanced tags (filters) on certain admin panels
Templates
The templates to modify the look & feel of the preferences:
http://sourceforge.net/p/tikiwiki/code/HEAD/tree/trunk/templates/prefs/