Thanks for the reply!
I recently tried to set up OFS and used it with some success talking to a SQL Server database with a simple form that had no code behind it. (I loaded it as an administrator, not a user, even though in that case, it wasn't necessary.) Then I created a more complex form in VS2005 that uses web services and has code behind it. It worked fine on my machine running it from within Visual Studio, but when I tried to deploy it to OFS, things got progressively worse. It eventually refused to run even in VS2005 on my own machine and I had to create a new project and move files over, one at a time, to get it working again. The error messages I was getting at that point were too vague to be helpful.
So... Figuring that I had probably messed up a few things in OFS because of all of my experiments, I completely uninstalled OFS and reinstalled it from scratch. I am now in the process of very carefully setting everything up, one step at a time. So far, I have done everything according to the deployment documentation for a standalone OFS setup. Unfortunately, the deployment documentation stops short of providing recommendations on the best way to organize your web applications within SSPs, etc.
At this point in redoing everything, I have not tried to deploy any forms to OFS. I'm just trying to set up the environment in preparation for deploying the form which uses web services and which will require a UDC. I created a new SSP and called it "Forms SSP". I set up a web application associated with this SSP and configured IFS support on it. I did not explicitly create a site or site collection within this web application because it created one automatically (/ssp/admin). This site does not show an option to create a DCL. I would not expect to need a UDC handy just to set up the initial DCL.
Sorry for the long post, but maybe something I included will tip you off to what I might have missed. Thanks again!