Is it possible to use the Natty BFB (Ubuntu button that opens the dash) in Precise?
I really liked the design of having the button on the menu as opposed to having it on the launcher.
I also liked the Dash launcher on the panel, it made the two bars seem more integrated and didn't make me dislike Unity as much. I don't like the current look either. As Manish Sinha pointed out in his comment above, there is currently no way to do this.
You've asked how to patch it, which goes further. It would be a good bit of work, likely. I think there would be two separate jobs, removing it from the Launcher, and adding it to the panel.
I don't know if you'd really want to do all this, and I'm not an expert on building these things, but I hope this could de-mystify the subject, a bit.
There is always a way in Ubuntu, but it isn't a configuration option, so you'd have to patch it in yourself if you wanted that.