Q:

OS X: How to give different icons and titles to simultaneously running instances of Firefox

I often run two different instances of Firefox simultaneously.
This works great, except that the various FF instances show up as identical-looking icons in the App Switcher (aka ⌘+tab), Dock, Activity Monitor, Force Quit (aka ⌘+⌥+esc), etc.
Also, the title that shows up next to the icon when the latter has the focus is the same string ("Firefox") for every instance.
I'd like to assign different icons or titles (preferably both) to each instance of FF.
How can I do this?

NOTE
There are several threads in Superuser relating to running multiple instances of FF, but I have not found one that addresses the specifics of the present post (namely: icons+titles, OS X, Application Switcher, Dock, etc.).  Also, one of these threads mentions a couple of FF addons that sound as though they may take care of this problem, but one of these addons is not available for FF 33.x, and the other one did not work at all for me (I was not able to get any distinction between simultaneous instances of FF using it).

1I start these instances in a Terminal console, by invoking short alias for:
/Applications/Firefox.app/Contents/MacOS/firefox-bin -P -no-remote &>/dev/null &

...and picking one of several profiles I have previously set up.

A:

First create a custom .app (e.g.: following this guide); then set a custom icon for the profile with this addon.

