Your last post indicated you were going to go ahead and try it ("Maybe I can try that.") It's possible we were all waiting for your success story.
I was looking at the LA service manual just now. The RGB board seems like it would have readily available component-type signals, but I don't know if they're usable, nor do I really care (Component sucks), otherwise I'd be all over this mod.
Let us know how your efforts go.