OT: How to examine ISOS for clues to bootup process?

[Deborah Armstrong]

* I will cross-post this to Debian-Accessibility in a few days. I've already
cross-posted this to the ubuntu-accessibility list*

This is a bit off-topic, but I don't know where to ask.

Is there a way, by simply examining the contents of a distro's CD or ISO
that one can figure out how to boot it up 
with access?

I started thinking about this when I ran across INX, a new ubuntu-based live
distro that contains only console 
applications, and includes BRLTTY. I couldn't figure out how either to run
BRLTTY or to get the console=ttyS0 
parameter to work so I could access it with another system running terminal
emulation.

I have looked before in the Isolinux directory at the text files with names
like f1.txt thru f10.txt; presumably 
they are the help screens that display when function keys are pressed. But
they often only partly tell the story. 

For example, I would have never known that on the new Debian Lenny CD, one
was supposed to press Down arrow to 
highlight the graphical install, then press Tab and type speakup.synth=XXX
where XXX is the keyword for the 
synthesizer. I learned this by reading the release notes, but with Lenny,
there were two non-inttuitive things: 
first you had to select graphical install and second you had to type
speakup.synth rather than speakup_synth.

With the server edition of Ubuntu, to perform a headless install, I had to
type "install debian_frontend=false 
fb=false console=ttyS0" and I had to type it in before the boot prompt timed
out and the installer started loading. One early edition of the server CD
let me just type this, another required I go through some menu first to
arrive at a boot prompt where this command line could be entered. 

With Lenny, there is no time-out. You can boot the CD, go out to dinner,
come back and press your arrows and tabs, 
enter your parameters and everything works perfectly.

Ubuntu desktop, which has both brltty and Orca built-in seems to have a
different process for each successive 
version.  And many ISOS want you to type some sort of target, to specify
which kernel to load, whereas others have 
you select that target with the arrow keys, whereas others have you pressing
some keystroke and then typing in 
parameters to an already specified target. And some have you pressing ESC to
get to a boot prompt, and others have 
you selecting menu choices or pressing function keys, then making menu
choices, and then pressing enter a couple of times. With some, you press a
series of keys to arrive at a boot prompt whereas others have no boot prompt
at all! I even found some variant of BSD that had you press a 
function key to arrive at a boot prompt.

It would have been easiest if I could have discovered how a particular CD
boots by examining some files in its 
mounted ISO. Is this possible?

It seems like the bootup procedures for each and every ISO are different,
and there is absolutely no standard. It also seems like the makers of these
distros rarely assume one will try booting them headless or with a visual 
    impairment and they rarely put a text file on the CD that clearly
documents this stuff.

What files can I examine to learn how the boot process for any random ISO is
going to run? Pointers to any URLS that document this would be useful and I
promise to RTFM!

--Debee