I'm not sure if you can inject components from a Java Bean, but I do know you can inject components from SSJS. As for handling dialogs, you may want to make your dialogs dijit/component driven. With a custom dijit this will allow you quite a bit of flexibility in handling the presentation of the dialog and by making a component with it's own renderer you can control the content of the dialog.
For injecting components via SSJS see my post here http://www-10.lotus.com/ldd/xpagesforum.nsf/topicThread.xsp?documentId=B1192058B062B07A8525783C006270C2&action=openDocument