I can't really speak for Epson as I use a HP with the airprint feature for my iPad2.
I have my main computer hooked up to the printer via USB and when I want to print from my iPad, I just touch print and it finds and lists the printer with the true airtouch feature. No software or anything else to load for the iPad.
I don't think it would be any different as long as the printer does have air touch and a USB port.
I have went as far as having a document print from my main computer and then touch print on the iPad, it justs puts it in cue until the first document is done, then prints the iPad document.