Check the PS3 HDD Forum for "USBLB Loader" threads (including Stickys, etc) and you will find several thousand posts on it in total along with USBLD Loader Guides in the "PS3 Guides" section linked at the top of your page. http://www.ps3news.com/forums/ps3-hdd-news/
In short, that is the closest thing you can currently use on a PS3 to run PS2 images from the PS3's HDD. There is no way to run PS3 game images from the HDD on the PS3 with it though... and you must have a PS3 that supports PS2 emulation already (4 USB ports, not 2 is the quickest way to know).
I'm closing this now, use the existing threads in that section if you have more questions on USBLD Loader.