I was just searching for the answer.
To display a search icon instead of the return key, you can use:
Dim JO As JavaObject = EditText1
JO.RunMethod("setImeOptions",Array As Object(3))
The key will then be treated as if you pressed the return key.
In addition, you can set the onEditorActionListener to respond to the key.
Dim O As Object = JO.CreateEvent("android.widget.TextView.OnEditorActionListener","Search",Null)
JO.RunMethod("setOnEditorActionListener",Array As Object(O))
Which will call the sub:
Sub Search_Event(MethodName As String,Args() As Object) As Object
Log(MethodName & " called")
Return True
End Sub
When it is pressed, return False instead of true to close the keyboard.