Does anyone have a solution or recommendation for connecting my 3100HD to the RGB inputs on my projector?

SA has a component to RGB transcoder available:

http://www.sciatl.com/customers/Source/752184.pdf

Is it true that in some instances, a simple cable converting CV to RGB, or vice versa (or VGA) works? You may wish to try a search for those on the web since I've seen them advertized and heard of some success, negating the need for a transcoder.

Perhaps some of these work and others don't depending on the equipment...

No, the signals levels and what they contain are quite different. Some RGB devices will output/accept component video through the RGB port, but they are 'programmed' to do so on the inside.