In order to get the sling adapter rebate, it does need to be ordered through an agent (which I can do for you). You would need to pay the $99 for the sling adapter up front, then once it is installed, you fill out a rebate form online at your dish.com account. 8-10 weeks after this, you receiver a $99 prepaid card in the mail. The sling adapter is auto-shipped to the physical address on the account as well.
If anyone would like for me to order it for them, please send me a PM with your phone number, or account number