Hello. My name is***** can help you with your question.
Larry, it sounds like you're just looking to put the buttons outside for someone to press and make the door chime sound. Is that accurate? If so then this will be an easy install. Although you will have to get the wires down there. Another option that is available out there is a wireless one. Actually there are several of those. In fact there are a huge number of them. Here is a link to that category on Amazon:
I probably don't have to tell you that something for 20 or $30 is not what you want. Make sure what you get will work over the distance that you need to get it to the door chime. Now, the solution does not make use your of your existing door chimes. If that's something you definitely wish to do, then you would have to wire down to the door if you're certain that there are not wires there already. Let me know if that suits your needs or if you have additional questions.