UDI, manufacturer of ISY994i, have discovered a way to hack an Insteon Hub and install a serial port that will communicate with the ISY994i. Apparently the Hub uses a serial port signals to bridge to it's Ethernet port internally, making it quite easy.
Europe uses slightly different frequencies for Insteon RF as well as the powerline frequency of 50 Hz. This would be needed for compliance with the national radio frequency enforcement people.
European Insteon devices must be used with the EU version of the Hub due to these feature changes. The mesh network works by synchronising to the powerline frequency to allow every device to repeat the signals simultaneously so the 50/60Hz is also important.
UDI has sent out several of these modified Hubs as a test bed for future expansion possibilities and apparently they work quite well. Many people ask about this in EU, as well as OZ, since ISY presents many good features, and Insteon works so reliably, but the Hub is about as dumb as HA can get. One of the staff at UDI has developed this hack and has published instructions how to do this.