I have lids that fit PET bottles, that clip onto my keggerator. It's quite effective.
He hasn't provided much more info than he though about carbonating with Sodastream. but if he's stabilized, than yeah Kegs probably the only option. If he has a bottle mead that wasn't stabilized, than he can rebottle it into beer bottles with some priming sugar and give it a shot.
Yes, like that, but stainless steel, like this:
http://bit.ly/152UdwN