you will be able to sneak him on, a few people when I was there did this, best way is to put him in front of you and go through the turnstile together as one person.... if you get what I mean.... just shuffle through....
If they are going to be sking you should def. get them a lift pass, if not you will regret it when you get to the resort and may have to pay the resort prices, If you just want to take them up the mountain a few times and they are small enough to get through the turnstile with you many people do this.