I started poking around in the webUI source files on the disk to find where the various bits get enabled/disabled and discovered that two variables determine the ssh options for rsync. One variable declares if this NAS is a "home" or "business" product and the other declares whether ryncoverssh is ON or OFF. The product must not be "home" ad must contain TRUE for the other variables for these options to appear in the UI.
I then tried to find out where the values for these variables came from, but was unsuccessful - they probably come from a perl file that's been compressed making them difficult to search.
So the next best thing was to search Google which led me to this:
edit //frontview/ui/resource/html/shares/shareoption_rsync.html ---- <this is for the shares rsync tab>
edit //frontview/ui/resource/html/backup/edtbkup.html ------------- <this is for the backup's edit tab
and replace the first "<script>" in both of these files with the below
--------------------------------------------------
<script>
//Added by me 4-12-09
NasState.ProductMode = 'ssh4home';
NasState.rsyncSshSupport = true;
--------------------------------------------------
So, just mark the product with some mode other than "home" and set rsyncshh to true at the top of each UI html file. Simple enough.
The newer versions of the files use "NN" instead of "NasState" - and so far the options appear in the UI. Now to see if the logic in the UI is enough to get the underlying code to actually work properly.

Cool, the connection test is working. For Dreamhost, using this UI, you have to supply the path to your directories as "home/userid/sub-dir" where userid is your account ID at Dreamhost. The "~" shortcut often used at the command prompt won't work in the web UI because it's hardcoded to start at the root "/" and append whatever you type into the path.