1.  cd <install media>/AIX
       NOTE:  you want to be at the same directory level which contains the 
              install.bin file

2.  tar -xvf 84939-370-000.tar 


Example:

cd /download/AIX
ls -l install.bin
  -rwxr-xr-x    1 root     system     53473774 Sep 09 19:29 install.bin
tar -xvf ../84939-370-000.tar