You can apply at Retailer.directv.com , that's how I did it... although both DSI and Perfect-10 told me they probably could have made the whole process go faster.
They have an option now on the retailer support phone line, you could try that... call 1-800-323-1994
Ours took about 6 months from start until the day I could log in an place/activate an order, so they may be right about the faster part.
DSI Systems and Perfect-10 both have websites where you can get their number, but personally I like perfect-10 a heck of a lot more. http://www.perfect-10.tv