I recently upgraded from Snow Leopard to Mountain Lion. After the upgrade I was unable to log in to my accounts. After days of frustrating procedures (reinstalling, disk utility clean-up, verification, password resets on terminal window...)

Question

I think I isolated the problem to a software issue. I called the software company and they directed me to a website with the following set of instructions:
Website: http://www.thursby.com/after-upgrading-i-cant-login.html
Instructions:
Support
FAQs
ADmtiMac v5 is not supported on OS X 10.7, Lion. If you have already upgraded to Lion, the incompatibility can cause a situation preventing you from logging in to any account. To remedy this situation, please follow these steps:
NOTE: If you do not feel comfortable performing these steps, please contact our Support Specialists for further help.
1. Restart the computer holding down the Command+S keys. This will start the system up in Single User mode.
2. At the prompt type the following commands (these commands will be listed above the prompt just in case you need to reference them):
   /sbin/fsck -fy    {hit the return key}
  /sbin/mount -uw /   {hit the return key}
3. Modify the /etc/authorization. At the prompt type
   vi /etc/authorization    {return}
This opens the file in the vi editor.  Then type:
   /AMHomeDirMechanism   {return}
This searches for the first occurrence of AMHomeDirMechanism (case-sensitivity is important).
do this:
dd     (don't press return, this deletes the line the cursor is on)
n     (don't press return, this searches for the next occurrence of AMHomeDirMechanism)
until there are no more occurrences of AMHomeDirMechanism (vi will say "E486: Pattern not found: AMHomeDirMechanism"). Depending on the version, there will be 3 or 4 occurrences.
Then:
   :wq    {return} (This saves the file).
(NOTE:  You may see "E138 Can't write ciminfo file $HOME/.viminfo!".  If so, please hit the return key, then continue.)
   exit    {return}
This last line allows the boot to continue, and you should then be able to log in andINSTALL ADmitMac v6.
I did this and it did not work. Redoing this several times over, I noticed that the issue is that Drive is "Read-only".  Changing permissions is above my "pay-grade" Any help will be appreciated it. I do not want to wipe out my hard drive and restart anew.

Answer 1

Addendum: I read on a post here (http://forums.macrumors.com/showthread.php?t=420169) about removing some kext files in order to trick OSX into thinking that there were no FireWire ports.
I followed the instructions and removed from /System/Library/Extensions/ the following files:
IOFireWireSerialBusProtocolTransport.kext
IOFireWireAVC.kext
IOFireWireFamily.kext
IOFireWireIP.kext
IOFireWireSBP2.kext
I restarted and BAM...Snow Leopard booted crazy fast and the mouse and keyboard worked instantly.
The System Profiler says "No FireWire ports were found."
So this tells me that the FW port is probably the culprit and is messing up the installation.
So how do I hack the Mountain Lion installer and tell it to ignore the FW port, which is obviously quite dead? Or is there something I can do to the Base system that is similar?