So here's the scenario.

I have sent my teensy 3.1 circuit to a client of mine
And now I need to update the code burned onto teensy without providing client access to the code

So is it possible to create an exe or an installer of a kind which on execution simply upload the new code onto the teensy?

Since the code is finally a hex file uploaded onto the controller I hope this must be possible
But on doing a quick google search i was not able to find any valid resource which would guide me how to go about it.