Creating a HUD

I need some method of projecting an image to the inside surface of - say - a visor. I've been looking at several options including microprojectors, but they just don't seem to fit the way I'd want. If this is going to mount inside a helmet, then I can't deal with any bulk. It has to be able to mount either on the forehead or between the eyes above the eyeline and project (with about an 80 degree FOV) on to the visor, while remaining completely unobtrusive to the human vision.

On top of that, I need to control the focus of the image such that the eye can "see" it from about 4-5 cm away. If you stick your hand in front of your face, you can't focus on it. I'm seeing a lot about focusing on infinity in other forums and such, but I haven't been able to try it yet.

Liquid Crystal on Silicon is another option as well. I need to determine what level of projection these provide, as well as a resolution. This will need to be a fairly wide image, but vertically narrow.