The Remote 4 switch connects to the control (CTRL) port of the Tensor and provides access to up to 4 modes of presets and functionality. See the Owner's Manual for a list of functions and configuration information.
It is simple to build your own remote switch using some normally open switches, resistors, and a 1/4" TRS jack. The tip and ring of the jack are connected together, and to parallel resistors for each switch. The other side of each switch is tied together and connected to the sleeve of the TRS jack, as shown in the diagram below. Each switch has a specific resistor value that the pedal reads. Use 1% tolerance (E96) resistors.
The switch modes are assigned so that useful functionality is available with one, two, three, or four switches. You can use any normally open momentary switches, such as momentary stomps, tactile, or arcade switches.