(HELP NEEDED) Editing and modifying NTFS boot.ini

The isuue is really curious. I was trying to get rid of a virus in my work laptop and I needed to restart in safe mode.
The problem is that I've discover that I don't know the password for the machine (only for loging as domain user) and the boot.ini file has been modified so it only starts in safe mode. I haven't found another sollution than editing the file from my knoppix 9 and removing the commands that force Safe Mode.

The main problem is that it doesn't allow me to save the file when I modify it (from vi and being logged as root) and I don't find the utility captive-ntfs which seems to be made for this purpose.

Can anybody help me to solve this issue? Even if the sollution is not related with knoppix the help will be useful.

I've also read that doing modifications over a NTFS file can be catastrophic. Could this be the case? I think that the modifications I'm willing to do over the file won't even affect it's size.... Any oppinion?

Thanks a lot!