I am not entirely sure why you would have problems with getting it to work. When I try to multibox with it using the exe I had made it to work with no problems.
I would try to use 3 accounts with pwnboxer but my laptop is not really good so I could only do so much with all of the lag that I get.
I would think to give you the swf file but then again to make it work for multiboxing you would have to do the same method that I had done to make it work in the first place so I have no reason to hand that out just yet.