How does one adjust tree bend factor in animation timeline?

I need to create a short storm and have been able to rock and sink a boat, and blow a dock and house apart, but I can't find settings using the animation timeline to adjust the tree bend factor or the wind for the grass. I'm rather surprised it is not obvious. Any ideas?

unfortunately this functionality of unity is not exposed to scripting API in unity 2.x but i think it changed in 3.0 because as people talk about it the tree system changed much. so wait a few days to see 3.0 it mihgt be possible there.

you can use your own trees with normal animations at this time.