What you could do is offer scripts or anything like that which they can use to compile Hiawatha for the embedded device themselves. Of course, you can mention all kinds of requirements (software and hardware) for that. That way, you make the whole process open (as required) while at the same time discourage people to start messing around with the device themselves. If you specify all the details, you are actually saying: this is complex, don't try this at home, let us do it for you. Which is more or less what you want.
What kind of embedded device are we talking about if I may ask?