Torchmate is run with either a serial port OR a USB port. There is not a plugin that I know of that will work with the Torchmate controller.
The torchmate runs with a FLASHCUT control system and it uses a self contained Z axis that is seperate from the controller so it will NOT integrate with Mach3 easily.
Next question is WHY would you want to change (;-).
(;-) TP