Unfortunately I'm not familiar with your machine so don't know about connecting an estop. Most machines will have a set of connectors for adding an estop. If you have any wiring diagrams look for estop connections. Most component suppliers will be able to sell you an estop button. Try rs components or farnell. You have a few different types of estop button. Pick one that latches when you press it. This means that you have to twist it to release it. You can get them supplied in an enclosure or seperate so that you can fit them into your own box or panel. If you have a look at my build log there is a photo of one I fitted to my own enclosure. Don't get a key release estop, those are just a pain.

Regards

Ian