1. Have a test/commissoning mode that is selected by a key switch.
2. Create a very simple web-server HMI of your choice only for testing/commisioning. When test/commissioning mode is selected, then use the web-server HMI to select the device to test, and the type of action ON/OFF, UP/OFF, DOWN/OFF etc. If the webserver is reachable by wi-fi, then the person doing the testing can use his smartphone.
3. Arrange a 'dead-man' switch connected to a safety relay. When the dead-man switch is half-pressed, the chosen action is activated. When the dead-man switch is fully-pressed or released, the action is stopped via the safety relay. The dead-man switch can be at the end of a long cable so that you can bring it with you everywhere around the machine.
N.B. You need to consider the speed of actuators. If the actuators are so fast that it is not realistically possible to remove the limbs that may be caught by the movement, then it is not possible, or you need to provide a system for 'safe low speed'.
N.B N.B. in case this is not clear from the above. All of this should be covered by a risk assessment.