Farstar,
You may have missed the fact that the "Accessory" post was made back in 2000. The link still works, but I had difficulty using the power tool sublink from that page.
In any case, I haven't seen any accessories listed for Ridgid power tools in some time. I can't say that it isn't here somewhere, just that I haven't had success with it.
But, with regard to an accessory dust pickup for your Radial Arm Saw, there are a few third party accessories on the market that are designed for use with compound miter saws, that should work fine. For example:
http://www.rockler.com/product.cfm?page=11312
For my old Emerson-made RAS, I simply made my own dust adapter.
CWS