The good news it can be easily done with a Arduino Board Nano! The board cost less than $30 on mouser.com but you will have to add extra components (relays to protect your computer and a darlington transistor network chip to drive those relays). The final board would be less than $60.
Any piece of software which can access to the serial ports can communicate with this arduino board so it is very easy to write a software as it does not require to implement special driver!
I will have a close look this weekend and let you know.