Yes Existing components can be extended. You will have to create a new dialog of your custom components to be used in new touch optimized UI in forms 6.2
This article should be helpful
https://docs.adobe.com/docs/en/aem/6-2/develop/components/components-touch-optimized.html# Extending Existing Components and Dialogs
That does seem to be the case. The problem I'm now encountering is that the ID that is assigned to the elements in the HTML portion of the form does not match the ID that is in the binding context so when the form validation runs, it cannot find the elements and they do not correctly validate.
The problem I'm having is that the somEpxression that the validation routines save in the list of failed elements does not match the somExpression of the elements on the page so calling the gudeGridge._getGuideDomElement() with the som expression of the failed element does not resolve to an element.
We have too much messy script to control the form elements and the way the page is rendered and the items cached makes it even worse.