I managed to -somewhat- dual box 2 Troopers with 2 machines, via the usual multiple PC method in IsBoxer. But as the rest have said, without macros its hard. I managed to transfer my main toons keymaps to my alt, but it was complicated. Each keymap had 3-4 steps.
First of all, I bound F for follow, G for assist. Then I made a keymap for 1,2,3 ( didnt test past those first abilities) with 4 steps. 1->target main with F2 2->Follow so the alt faced the same way ( most of the time) 3->Assist 4->Button Stroke (1,2,3,4)
This was my noobist version, since most of the time I relied on a macro'd game, and this is not convenient, since most times it needs a multiple stroke on the button to get him to attack.
However, some people in my guild saw a guy multiboxing normally, without "flaws" in his synergy. So, I assume even with it's current mechanics, dual and even multiboxing is viable. I would appreciate any more infos!