Chances are that unless the DCX team makes the dialog maker, it won't happen. For someone else to make it and keep it updated and always working with DCX considering how often DCX gets improved would be too hard for most people to bother with.
Having more dialog control has been requested before and would be useful. You can always post a feature request for everything you'd like to see in mIRC's own dialog options. With more people supporting it, it could eventually be added.
