How do I install software on new HD on PS3?

I believe that once you put the new drive in, and boot the console, it will take you through the process of re-installation. I haven't tried this on a slim, but on fat PS3's, you just put the drive in, boot the console, and follow the onscreen instructions. If you want to restore your data, you need to connect an external hard drive via USB (With the original drive still in the PS3) and navigate to Settings>Backup Utility, and select "Back Up" and then select your external hard drive. Once it's done (It takes a while depending on how much stuff is on your PS3's hard drive) put the new hard drive in the PS3, and use Backup Utility and select "Restore"