We make the tabs and accordion work by using special css class names in conjunction with markup designed for use with the widget. So the markup for the jQuery accordion for example looks like this:
<h3><a href="#">Section 1</a></h3>
<p>Section 1 content.</p>
<h3><a href="#">Section 2</a></h3>
<p>Section 2 content</p>
<h3><a href="#">Section 3</a></h3>
<p>Section 3 content</p>
<h3><a href="#">Section 4</a></h3>
<p>Section 4 content</p>
and we inject a little bit of script at the bottom of the page to hook it up (and any others on the page) like this:
So, if you were using some other widgets you would have to create a template with the right markup and then add some init script to the bottom of your layout.master page. Our script is injected by our ScriptLoader control but you would put your in layout.master.
We only have a few widgets baked in already but really some widgets require more initialization code and options, so while adding the tabs and accordion was low hanging fruit because they just work and don't require a lot of configuration, other ui widgets may not be quite as easy to add.