This question received the following responses via a social networking site. I removed the names of people that posted.
"All rules like with the regular king shot. When the king is down, he's down. But your back needs to towards the king and the throw needs to go through your legs. It's actually quite easy. Mostly..."
"It's just easy. Your back needs to towards the king and the throw needs to go through your legs. It doesn't matter how the stick fly, an angle is here allowed, but take care, is not easy any time. but funny. I know that the beginning of the sure shot wasn't in switzerland, these rather be in sweden. but the switzerland kubbers often say they are the inventor of these special king shot. but it's not true. thx cmc :)"
"This was the house rule on Kärne up until we started participate in VM 2005, so I've practiced it for 15 years. There are 3 main points to remember executing it:
1. Take out an imaginary line 10%
2. Actually look and focus on the King 40%
3. Make a 'total follow-thru' when throwing 50%
Make up an imaginary line between the king an a spot of grass/between the grass on the baseline. Place yourself above that spot an 'look' at the 'line' when bending over.
Be sure that you focus on the King, watching between your legs. If needed, use your free hand/arm for balance support, leaning on it to steady your upper body.
When throwing, make sure you really really let your arm and hand point at the King after the baton release. This is the most crucial part of the routine!! You will notice the difference.
Watch YT-clips from the Sure-shot tournament, like last years final. Notice the lack of the last 'follow-thru' part from Kubb'Ings