You could default to SR3 rules for drones moving at high speed

(You'd just need to translate the damage codes over.)
The power of the thrown object is going to be set by its speed. I don't know that SR has a mechanic for determining speed, but I suppose some sort of Strength or Athletics test would be appropriate.
Once you determine speed, set by the strength test (with a target number based primarily on the mass of the object), the number would be reduced by the object's drag (which will be significant with a dwarf trying not to be thrown). You'll also want to modify the target number to hit, because the dwarf is not perfectly balanced and aerodynamic, and is indeed actually moving and shifting his center of mass. This would be a hefty modifier as well - but that determines whether you hit or not, not the base damage of the dwarf-weapon.
Once you have speed (in m/turn), I'd translate from the SR3 rules - speed/10 is the power. Damage level (for a vehicle or other object getting hit by a metahuman) is also based off of speed. Speed of 1-20 is 0(0). 21-60 is L(1). 61-200 is M(3). 201+ is S(6). Arguably, a troll is closer to a vehicle, and so the damage level goes up by a notch. Also, based off the rules, it could be read that a metahuman hitting another metahuman would also increase the damage level by a notch.
(Remember that m/turn converts to mph when multiplied by .75, and km/hr when multiplied by 1.2. So a dwarf travelling at 100 mph translates to 133 m/turn, which is 10M damage - about as much as getting hit by an Ares Predator.)
Also note that damage will also occur to the dwarf. If the dwarf is hitting a solid object or vehicle, the damage level will be:
Speed of 1-20 is M(3). 21-60 is S(6). 61-200 is D(10). 201+ is Asplode(10 + 50% to the power). Power stays the same.
Edit: As an aside, a dwarf's terminal velocity is going to be pretty hard set. A skydriver's terminal velocity is 124 mph. With arms stretched, it's still 120mph.
That translates to 160 m/turn - 16M damage to a wall or building. 16S to another metahuman. No matter how hard you throw, you won't be able to beat that, without putting your dwarf into a bullet suit.
Second edit: Record for intentional super speed skydiving is about 320mph. So if the dwarf WANTED to really splat, he could manage 32S, or really, arguably, 32D to that vehicle. But at that point, he's going out of his way to kill himself. Granted, "dwarf bullet thrown by dragon with enough force to destroy a helicopter" is still a pretty awesome way to go.