I've had very limited luck modifying this page. We've not had much luck with approaching either RSA and Juniper regarding getting additional information/meaningfull examples of modifying the template. For the most part we kept it vanilla, except adding the log-in banner, and forcing it to open a browser window in a particular size.
In retrospect, is has prompted us to also take a look at the RSA toolbar token. It looks promising, but seems to be lacking the flexibility, or rather configurability to make it work with the Juniper sign-in pages without having to manipulate the template. I'm actually very surprised that RSA does not allow you to customize the fields you want the toolbar to populate.
Back to the SoftToken sign in template, I'll see if I can dig something up, but again, I'm not sure how useful it may be given how little we've done to it.