In this Thread i will explain you how to install GTA 5 on your PS3 and fix the the Stuck at X/8486 MB.
1. Go to your Game Data Utility and find Grand Theft Auto and Grand Theft Auto - Install and Delete both.
2. If you already Deleted them go to your Network Settings and Disable the Internet.
3. Now go your GTA 5 and DON'T Install the Update press Circle to Cancel it.
Your GTA 5 will now Install the full 8gb without any Stuck Issues.
If you Installed the 8gb and played the Prologue restart your GTA 5 and start Install the New Update *1.27*.
I hope i could help you out with this .