Terryx-you may want to ask suck a quistion here.. http://psx-scene.com/forums/usb-hdd-discussion/ From there you will get the support you need and any anwears you will want..
As for USB Advance your in the right direction.. Your HDD needs to be formatted to FAT32 and from with in the link I had givein you here it will tell you where to get the programs needed to install the .ISO of your games.. (You just cant drag and drop the .ISO's with in your FAT32 HDD-They will not work that way)
Plus check out http://sksapps.com/ That site has all the files you seek plus the Tutorials are top notch.. Hope this helps.. If not just go to the link I first gave you and ask for help further there..