You can RGH a Zepyer, however their a pain to do and can be unreliable. A lot of people don't like to RGH them for that reason.
I don't RGH consoles and its been years since I've Jtagged one so I wouldn't be the best person to ask. Any reputable modchip seller would be able to advise on if what their selling is suitable for a particular console and provide an installation diagram.