This a package maintained by freestyler. So pkgs.org points to his website. I would say this is logic that you cannot download the package.
Did you try to reach freestyler? Many members on the porteus forum would be happy to have news about the bad boy.
You know usm command line, you can build cuda toolkit from source with:
[url]root@porteus:~# usm sbo -s cuda[/url]
Voltaire: Le mieux est l'ennemi du bien.