You have to use conditional formating for each control you want to disable or hide (or set textboxes to read only mode, but this isn't easily changeable afterwards any more.) So I would suggest that you really use conditional formatting for your controls or sections.
One way you could do this is that in your onload event you set a value to a dummy node (with code, e.g. XDocuemnt.DOM.selectSingleNode(my:myFields/my:dummy).text = 1; ) then set a condition to all of your contorls which hides / disables them when dummy is equal to one.
Hope this helps.
Listen to Motörhead cos they play Rock'n Roll :)