Custom Entry view like SearchBar

I'm trying to create a custom Entry view that's similar to the SearchBar view (I know the SearchBar has an X for clearing the text, but want to implement my own). I want to add an X at the end, so that users can clear out the text (just like the UITextView for iOS and TextBox for WP8). How would I go about creating this? I can easily do this in an .axml file for Android with a FrameLayout, EditText, and Image, but keep running into a wall doing this in Forms. Thanks!