I might be misunderstanding your issue, but please keep in mind that webview will *automatically* scroll the page to make sure that the input item is visible even when the keyboard is displayed (if you are managing the size of webview properly).
So, I guess my next question is how are you resizing webview when the keyboard appears and disappears?
It should be similar to this:
Sub IME_HeightChanged(NewHeight As Int, OldHeight As Int)
wv.Height = NewHeight
End Sub
(the above code assumes that webview is full screen)
Basically, you should NOT be modifying the .Top property of webview, but instead modify the height of webview depending on if the keyboard is displayed or not. This way when webview gets "crushed" it will allow scrolling the page up or down to make sure the desired input field can be made displayed even in the reduce vertical window space when the keyboard is showing.