HotBurn and HotBurn Pro and updates are still available at the Iomega site.
The software is neglected and semi-obsolete. Iomega seems to be making no effort to promote it, and may primarily use it for their own rebadged drives. Although the drag & drop packet writing software is mentioned, there is no information about support of any UDF standards. There are also no UDF readers on the site.
One possible solution to your problem is to find someone in your local area that has the HotBurn software on their computer using any Windows operating system. The discs could then be read and burned to a standard ISO 9660 CDR. The software is packaged with Iomega drives, so it may not be too difficult a task to find someone with the software.