Came across this thread when I was in the same situation. I finally figured at least 1 way to do it. You probably figured it by now since this thread is half a year old. However, I figure I should share how I did it for others who found this thread looking for answer also. Here it is...
1) Put the item you want to throw in your inventory (out of any backpacks, etc)
2) Use the "Throw (X)" class action, brown colored button
3) It will allow you to select anything you can throw in your inventory
4) LeftClick the item you want to throw
5) LeftClick again at your target and throw it
If your item is in a backpack, when you select an item to throw, you can select your backpack to open it, but it won't allow you to actually select an item inside the backpack to throw. If you proceed anyways, it will throw the backpack instead, the backpack would be destroyed, and ALL the items in your backpack will be splattered all over the floor! LOL!
