Help! Sleep training

HELP! Now I know we waited a little long to do this. But I'm pregnant and want my 15 month old in his own bed before this baby gets here. He's also just not sleeping well and I'm hoping him sleeping on his own will help that. How can I help get him to sleep on his own in his own bed the best way possible? I don't want to do the cry it out because it just worries me and I know it will make him scared that mom isn't there after all this time. He's also very stubborn and strong willed, so even with the route of me sitting with him, how long of him crying is too much till I need to give in?