"Support": sure! I won't "do the work" for you though :)
Okay, Just reading through the django code, and I'm seeing that the help_text is _not_ emitted in the field's widget, but in the _html_output method of BaseForm In other words, you don't need to update the widget. Useless doing so.
So, to ask about the options above, do you want to override the behaviour of the admin, or your own code?
Do you use this often enough that you'll want to change the behaviour of as_p, as_table or as_ul, or are you happy to just take control of things on that side, yourself?
The standard behaviour is to put the help text into <span class="helptext">xxx</span> ... its perfectly possible to use jQuery to replace all of those instances with whatever HTML you want.
So... which route is going to get you what you need ?