Hey guys.
I don't really know Keil's uVision system at all. I've had a lot of success with integrating Unity into my workflow using IAR's Embedded Workbench and other tools, though. So starting with that caveat, I'll try to help out.
It appears from looking at the manual that Keil supports pre-build and post-build steps. That's perfect!. What we really want to do is get a fully-working makefile (or rakefile if you prefer) to run your tests. Once it works, we will trigger it in our pre-build step so that all our tests are run before we do a release build. (If that becomes a pain, often IDE's have "external tools" or a way of triggering a command line task through a keyboard shortcut. Those can also be used).
Here's some help on how to put your system together:
Here's some help on getting Unity working with make:
Finally, if Keil supports a method to trigger events based on the currently selected file, it's really helpful to trigger small single-test builds based on the current file.
If I can help with any of this, feel free to fire questions my way. I'll do my best to keep up.