I don't believe there are any publicly available apps which properly support repacking those files.
If that's the case & if you are serious about it then you will need to:
*Brush up on your C++ skills by diving into some C++ programming.
*Possibly read a/some C++ book/s- I recommend this one: Mcgraw Hill - C++ Demystified.
*Get the zlib source code-
http://www.zlib.net/.
*Compile it.
*Import the generated dll/lib into your ca2 decompession/compression app.
*Study the ca2 specs-
http://wiki.xentax.c..._MotorSport_CA2.
If you get this far you will probably know the how to do the rest on your own.
Have fun.
KM