I use SHtml.jsonForm in myjsonclass.show to wrap a jsonform to the HTML page with the following command:
<div id="form" class="lift:myjsonclass.show">
It works fine.
The SHtml.jsonForm method defines a random id for the form tag, I wonder if there is a solution to get that id and use it in the HTML. It will make easier for example to apply form validators in Javascript.