Possible to boot DLC?

I was wondering if u can download some DLC that you would normally find on the PSN Store, but you find it on say a PS3 Hacks forum; anyways is it possible to download and save that file onto your PS3 and load it as if u purchased it through the store? By DLC i mean things such as songs for Guitar Hero/Rock Band, or the expansion to Oblivion - Shivering Isles. Pretty much game addons.

Are there any websites out there that have such things you can download and put in your PS3? ive looked for hours and hours on end and couldnt find anything on google.

I really appreciate the help, thanks alot.

I was wondering the same thing. If someone downloaded one of those $10 games could you transfer that file from you ps3's hard drive to another machine and play it?