Ice climbing in Norway is excellent and the ice season is long. The potential for unclimbed routes is still huge, but foreigners have really opened their eyes for Norway, so you need to be quick if you would like to open new routes.
The waterfall is located close to Hemsedal. Hemsedal is a small town approx 4-5 hours by car from Oslo (depending on road conditions and how fast you dare to drive: speeding tickets are very expensive in Norway).
You could also fly in to Bergen on the west coast and drive approx. the same number of hours to reach Hemsedal. Then you'll see some great fjords and many many more icefalls on the way.
It's really not easy to give an exact route description, but I would say there are 3 main "areas" (this is really open for discussion since you can make hundreds of variants on this wide waterfall): Left, middle and far right. The middle being the most straightforward. The left side may be somewhat tougher (also higly dependant on exactly where you climb, but there is a very serious overhang here). Finally, the far right calls for some serious mixed climbing. Its also possible to start up the middle and traverse right to climb the right side of the rock formation dividing the middle from the right sections.
Well, as you understand: you can just "pick and choose" your own line.
Bottom line is that this is a very serious climb. You should have done quite alot of ice climbing befor you try this. It's also very important that you evaluate the conditions before you go. You should know what good and bad ice sounds like before doing this.
The standard stuff for long ice routes (assuming you're not going for the mixed lines to the right which I don't know much about):
2x halfropes (I like 60m on this when abseiling), crampons, 2 ice axes, 10 or so ice screws, helmet, some extra rope to make abalakovs and motivation.
External Links This link will give you info from the ski resort and weather/condition info