Normally, you can't read files from filesystem with browser-based scripting, because allowing this is a huge security risk as Internet sites can now read files on your system!
However, I am aware that Netscape browsers (including Mozilla, Firefox) are designed with a "security manager" that allows browser user to specifically override certain security policies on their system. I'm not too familiar with these though.
I think some of the links on this page are relevant:
https://developer.mozilla.org/Specia...ty&language=en
However, it is important to note that even by tweaking the security manager you will still likely not be able to do things you can with IE because there is no comparable infrastructure as ActiveX in Firefox. At least I don't think you will get anything that allows you to manipulate an Excel spreadsheet.
