If your download from R* is shit, use this method and just get everything from MEGA:
Source:
http://www.reddit.com/r/GTAV/comments/328e2u/gta_v_rockstar_preload_is_broken/
This is confirmed working: If you haven't made much progress downloading the stuff, use fast download using MEGA link:
https://mega.co.nz/#F!N91DxBLJ!mO4qwYEfgcq4hPXUqlEdsA You have to download all RAR files in order to unpack it.
Unrar password: "www.intercambiosvirtuales.org" (without quotes)
Otherwise, search for a torrent that offers the same files if you only need some of the setup files.
INSTALLATION
If you used the MEGA files, unrar them first using the password.
After that, place all files in c:\Program Files\Rockstar Games\Grand Theft Auto V
Run GTAVLauncher.exe. It should see that the download is finished and it will proceed with the setup.
You can test to remove a file from the directory (for instance /x64/metadata.dat). The download manager will download that file. After that you see this:
https://dl.dropboxusercontent.com/u/21558454/GTA wachttijd.png which means the download is finished. That is what I did.