There is an API call to do it however it is not currently documented.
POST http://chatdepot.twitch.tv/room_memberships?irc_channel=CHANNEL_NAME&username=USERNAME_TO_INVITE&oauth_token=CHAT_LOGIN_OAUTH_TOKEN
There is an API call to do it however it is not currently documented.
POST http://chatdepot.twitch.tv/room_memberships?irc_channel=CHANNEL_NAME&username=USERNAME_TO_INVITE&oauth_token=CHAT_LOGIN_OAUTH_TOKEN