Ok firstly the best way to patch the system is to use the latest recommended patch set. This will include everything you need, security patches, bug fixes etc.
you can download the latest recommended patch set, from www.sunsolve.sun.com.
Make sure you read the readme that comes with it.
Most important take a backup of the system first, or if u have mirrored break it.
Uncompress the file, and un-tar it. You'll need plenty of temporary space, as well as space in each file system, (depends on your layout, if you have all the filesystems under 1 mount point or not).
Ensure you take the system down to single user mode, before you start the patching. Then just run the install script.
Once the patching is completed, you need to reboot to load the latest kernel version. Delete the un-tared directory, and re-mirror if u need to.