This code is just a standard PIX code interim release with bug fixes. You upgrade your existing PIX to it just like any other upgrade, in that you TFTP the code onto your PIX and then reboot it at your convenience.
There are detailed upgrade instructions here:
http://www.cisco.com/warp/public/110/upgrade.shtml
You mention the 6.2(4.101) image in your post, but if you're currently running 6.3(x) software on your PIX then I would recommend you use the 6.3(4.120) code release available from the same URL.