How about a place to put where you're going in champion select?
Something like this: http://i.imgur.com/fMas3MG.png
That way, even that teammate of yours that pays 1% of attention during champion select can still tell what's going on. And each player doesn't have to enter anything in there, so it's not like it'd defeat the possibility of someone choosing Ryze and saying they can mid or top. Maybe even don't let people enter it in until after they've locked in their champion. To me, it'd seem like it'd be easier to tell what's going on to have where everyone's going over there, rather than them scattered throughout the chat at the bottom that you may have to scroll through to see where each person said where they're going.