The Telestrat provides a second joystick port on the right of the machine which will accept either a two or 3 button joystick or a 1,2 or 3 button mouse.
The mouse must either be Telestrats own Mouse or an Atari/Amiga style mouse (but in this last case, you have to code the routine, because atari and amiga joysticks sends acceleration, and bits on the joysticks port does not work in the same ways than standard joysticks)
The current Telestrat mouse drivers only permit the direction of a mouse to be detected and not its acceleration or speed as is expected on Amiga, Atari and later machines.
However it is perfectly possible to enhance the driver to handle this properly.
For hardware details about the Telestrat mouse together with the electronic curcuit see here.