[Curiosity]

In mozilla.org, there is a page of instructions for setting up command line options for Thunderbird. There is a list of arguments as well. This page is at:
Mozilla's Command Line Options

The instructions for Macintosh are these:
On Mac OS, create a text file with the following syntax:

type:TEXT
creator:MOZZ
containing:ARGS: -P myprofile

That page is not clear on what you do if using Mac OS. Once you have made the text file, what do you do with it? Does it have to have a particular name? Does the creator in the text file have to be "MOZZ"? Why not "MOZILLA"? Is the profile name "default", or the cryptic series of characters representing the folder in the profile directory?

[Mithras]

Wow, I'd really be surprised if that is still the case. Very few apps pay much attention to type/creator codes anymore.

[Curiosity]

That article says that the code is 4 characters. The text file is more than 4 characters, so how does it work?

[Big Mac]

The codes it's talking about are type and creator codes, which were used extensively in the classic Mac OS and heavily depreciated in OS X. OS 9 used those codes for file-application associations. It seems to suggest that if you create a text file with those type and creator codes and then put ARGS: -P myprofile in the body of the file, when you open it Thunderbird will read the file and have its configuration changed accordingly.

[besson3c]

If you are trying to start Thunderbird with one of these command line arguments, you can do it one time only by CDing into the Thunderbird package, finding the app, and doing a "./Thunderbird.app -argument". Add a "&" to the tail of this to open up the app in the background.

[Curiosity]

I did some poking around and found an easier way to do command line arguments. I can use the Terminal and input: /<path-to-thunderbird>/Thunderbird.app/Contents/MacOS/thunderbird-bin -<argument>