According to the manual, you can record MIDI output from the Roland unit to your PC via USB cable or MIDI cables.
Looks to me the Roland unit should be able to drive the T4 as well, depending on what you want to do with the Roland output.
You should be able to use the Roland style into the T4 and set the T4 voices via Mixing Console.
Could be you would have as many as 16 voices (Roland = 8 and T4 =
playing the Roland style this way.
Since this is not a Yamaha arranger item, would you want to address this through e-mail?