A system that is usable with a well may include a piston, a primary control subsystem and an override subsystem. The piston actuates the downhole tool, and the primary control subsystem may be connected to at least one hydraulic line in order to move the piston in response to pressure that is communicated to the tool via the hydraulic line(s). The override subsystem may be connected to the hydraulic line(s) to override the primary control subsystem and move the piston in response to pressure communicated to the tool via the hydraulic line(s).