No, that's exactly what I wanted, Ivan. Thanks.
The property itself is to be hard-coded, not it's value.
This may be obvious to most Sitefinity users, but for some reason it wasn't obvious to me until just now. For anyone else who might benefit, this is what I did:
In the user control's code-behind, define each property that you want to be able to assign the value from the CMS/UI, like this:
.myProperty = value;
When you drop the user control on a page in the CMS, click its Edit button, and you'll see and be able to change the value of MyProperty. In my case, this is a hyperlink to another page defined in Sitefinity CMS but which will not appear on any navigation menu.