So I upgraded my DNN installation from 5.4.4 to 6.2. At first sight it all went smooth but starting to test stuff there are several things I need to adjust.

One of the problems I'm encountering has to do with jQuery UI tabs. They are not workin anymore in my custom module

I have removed all my code that was loading the necessary scripts (jquery-ui and jquery.ui.tabs) since DNN6 Now includes it.

So jquery-ui gets loaded but no tabs. How do I correctly register the jquery.ui.tabs scripts, where is it located..I only found dnnTabs inside js/dnn.jquery.js? I do not wish to use dnnTabs but jquery ui tabs itself..

I've tried adding 
DotNetNuke.UI.Utilities.ClientAPI.RegisterClientReference(Me.Page, UI.Utilities.ClientAPI.ClientNamespaceReferences.dnn),
DotNetNuke.Framework.jQuery.RegisterJQueryUI(Me.Page),
DotNetNuke.Framework.jQuery.RegisterDnnJQueryPlugins(Me.Page),
DotNetNuke.Framework.jQuery.RequestUIRegistration(),

And any combinations of those and I tried registering my jquery.ui.tabs.js file the way I used to do it but with no success..

Using the jQuery.RequestUIRegistration() method will register jQuery as well as jQuery UI. However, in order to make use of the dnn jQuery UI plugins, you need to call jQuery.RequestDnnPluginRegistration(), which will also register jQuery and jQuery UI too. As for 'styles' around the plugins, these are located in the default.css in all 6.0 or greater installs.

View this page in the wiki, it also leads to the individual plugins and how to properly utilize them (requires some javascript).