You can use reflection to call findAll method. This method will highlight the results and return the number of items found.
Dim WebView1 As WebView
Sub Activity_Create(FirstTime As Boolean)
Sub FindAll (w As WebView, s As String) As Int
Dim r As Reflector
r.Target = w
Return r.RunMethod2("findAll", s, "java.lang.String")
@Erel: You are absolutely correct. I ran it on two OS 4.03 devices and both did not highlight the search. But then, after you mentioned it, I ran it on a an OS4.2 device and it did highlight the search.