EditBox and InputMethod

I have an EditBox in my app that works nicely with the system keyboard. Is it possible to replace the default IME with my own?

What I want to do is this: When the system keyboard disappears, the EditBox looses focus. When this happens, I like to put it back on focus with my own IME instead - which will be using a set of buttons on the same screen as keys. When these buttons are touched (pressed), it should insert text into the EditBox at the cursor position.

I see that EditBox inherits IMEDelegate as well but do know enough to see how I can use this.

Appreciate any pointers.