A few years back I was able to send a fast train with Atomic Browser and TW's mobile site.
You set up a fullscreen shortcut to switch to the next tab, then you arrange all the attacks in the same place on the screen (by scrolling them all the way down iirc) and you put the browser in fullscreen mode. Then you just tap OK>Next tab really fast until the train is sent. My fastest train was about 400ms from start to end, I think.
I don't have an iOS device anymore, so I don't know if this still works. Try it and see.