Unfortunately this isn't easy. Because canvas drawing in iOS isn't optimized for speed, I'm instead using <div> tags to draw each touch object. The only way to get lines between them is to place a canvas object -behind- the multitouchxy widget, and use it to draw the lines.
I have done something similar to this, but the interface is fairly complex and there's no easy way to break it down. Also, it runs in the new version of Control (not the one in the app store) so it might not be that useful to you unless you can compile the new version from source off GitHub.
Sorry I don't have better news... - Charlie