Hmmm. I\'m having this exact problem and I just downloaded DT Register today. Although I\'m not using Joomla 1.5, I\'m using 1.0.12.
I\'ve updated Joomla to 1.0.15 and jEvents to 1.4.3. When I first attempt to add a custom field, I can see that more options are there but when the page finishes loading, I only have name and type available
eperry - as noted in your support ticket, we fixed this on your site.
For everyone else, there was still a problem in Joomla 1.0.x sites but it was fixed today and the download package was updated. If you are having this custom field management issue, download the component again. The two admin files listed in the previous post were modified.