You meant, like a moving-cockpit simulator? As in, someone would be on the robot as it moved? Well, it has been done, the most notable example being the various RoboCoaster versions.
Well, the first thing you will need is very tightly-set hard stops, and paid-up health and/or life insurance. That robot can easily crush a human being without even noticing. And even if you hard-stop every axis so as to make it impossible for the robot to crush a person against any obstruction (very difficult, but possible), the robot is still capable of inflicting accelerations and decelerations that can cause serious injury (like neck whiplash). RoboCoaster variants have special hardware mods to satisfy safety requirements, and have to be certified by the same agencies that approve carnival rides and roller coasters.
As for interfacing, about the only option available is going to be RSI-XML, which will probably require an additional realtime Ethernet card from KUKA. And once you have RSI-XML working, you'll still need a good deal of pre-processing on your external system to convert your joystick inputs into realtime motion commands that the robot can use.
K350 strenght, have a look at this video:
