There has been some interest in the Decompressor but in C#, so that a popular modern language can be used. I've done it. It only supports Rare games and I will not be porting the rest of the compressions to C#. You are free to include this in your programs.
Oh and in my haste didn't do any exception handling, so add your own wrapping your calls.
http://goldeneyevault.com/viewfile.php?id=229