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 tried to find a Q&A about removing the 'BFB' that opens the dash, from the Launcher, but I couldn't. I have some suspicion it's out there, though.
To put it in the panel, you could write an indicator that would go into the Panel--each of the elements in the panel is an indicator program, usually their own package, like indicator-session, indicator-appmenu, etc. Challenges there would include getting it to appear on the left, while avoiding collisions with the window-close buttons.
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.
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.