I haven't been able to reproduce it/make it work again since but sometime yesterday after a number of attempts at changing the order in which I start HKN and the 2 AION clients, and playing with mouse broadcast I had key and mouse broadcasting working - sadly I haven't been able to achieve it since - it seems by default keys and mouse don't actually go/reach the windows but somehow it can in some cases (I was trying to reproduce it today, making the guess that maybe it has to do with quitting only 1 of the clients and that was somehow disabling GG or something like that)

anyway I think there is hope - would one of the SW box author want to try to make it work (you can download the beta client for free and get to the login screen and try to get broadcasting to work there)