Please note that this is a developer support forum. You want to use http://reddit.com/r/twitch or http://help.twitch.tv for questions related to streaming.
That being said: Of course you can, it just won’t be HQ/HD. For “max quality/bitrate” you would have to be able to stream 3500Kbps(3.5Mbps) upload to a twitch server. With what you have, you may receive comments related to “potato” or “toaster” quite often.