Is possible to implement it in Adminer?
Feel free to implement it yourself, instructions are at http://www.adminer.org/en/drivers/. I will not personally implement it because I don't use Firebird.
I've developed a first version of firebird driver for adminer. Since this is the first entry in google search, my comment and solution hopefully helps.
Here is the files and usage instructions: http://mindfav.com/index.php?s=blog&id=11
Thanks, this is now in Git.