thats not easily teachable. its something ive just always been able to do, and thought it was cheating growing up (never really focused on reading music in lessons). id advise playing by ear on piano first, that should help if anything will.

i think it's something you can, or cannot. some born talent or so
i've been playing guitar really long, and i simply can't play anything by ear. i have a friend though, who never practised, yet he just can do it...

i myself have just given up trying... lol :-)

I don't think so, it's much easier for me to play it by ear on a piano than a guitar.