No this would never work. The Rho.ORM module depends on the database module (Rho.Database) which is implemented in C++ in the rhodes framework (it doesn't come with your browser).
I think you misunderstood. My app is running on Rho but I have fixed the port and am trying to connect to it through a browser. I am still running a rhodes app. For the same app on the same port I get intermittent success in simulator, but nothing in any browser, whilst the same pages are being viewed at the same time.
I don't think that the JS ORM stuff relies on custom browser extensions as the Motorola web kit browser is not available on all target platforms.