Codexata is temporarily down but will be back when the owner gets back in town.
In the meantime, here is another link you may not have:
and their board: http://www.codexataforum.cjb.net/
The famous Polish download sites carry such files as and when people post them:
There are more, these are just a few of the better ones.
To get new keys/ids (Stream or anything else) into the EEPROM key files, it is necessary to edit the files on the PC. That can be done directly using any old hex editor (but you need to know where in the file to edit), or it can be done using an editor made specially for the job. There are many different layouts of eeprom file in use and you need an editor made for that layout (or at least, one which supports multiple layouts including that one).
Editors are often downloadable seperately (PicBinEd is particularly poplular and supports a wide range). Sometimes - as with the Irseto files - they are packaged with the hex/bin files themselves.
Some files support the update of keys via the remote control of the receiver once the card is placed in the CAM. Use the "search" function of this board to lern more, as it has been discussed many times in the past.