has some packages on their travel pagehttp://www.snow.co.nz/travel/index.asp
It is also a good web site to easily access all the snow reports for all areas, and other general information.
Camper vans are popular with foreigners for ski trips. It means you can be flexible and go where the best conditions are. Has not appealed to me, especially driving a campervan up our ski area access roads, but lots do it. The rental companies supply the chains, which you must carry. In NZ, we live below the snow line so it is as cold as you might think. You drive up to the snow line each day to ski. There are plenty of camping rounds equipped for motor homes so you have access to kitchens, bathrooms and TV lounges. You don't have to sit in your van all evening, it is just somewhere to sleep and store your gear.
You cannot take the larger campervans into some of the club ski areas, like Craigieburn. This is because the roads thru the beech forest are too narrow, but you can take them to all the commerical ski areas.
Ski Express is owned by Tourism Holdings Limited, who own 'Maui' campervans, one of the largest camper van companies in NZ. So I expect they have campervan ski packages. They used to own Treble Cone too, so always have good packages for there, like a free pass each day, but they sold the ski area to buy more campervans. They are a lot more profitable than a ski area in NZ where you have a short 3 month season in a good year.