In this paper we present our low-level software framework that allows human neuromuscular properties and behaviors to be programmed modularly onto biologically inspired prosthetic devices. Specifically this software framework is used at the lowest level of the anatomically correct testbed (ACT) hand. It abstracts away from the robotic details and allows users including biologists to program individual muscle physiology, multiple muscle synergistic activities, neural commands, etc. independently. Our system has been designed to be fault-tolerant with the idea of safe and continued operation of prostheses if a new prototype behavior were to perform incorrectly or outright fail. Example coding of Hills model is shown.