OK...you can reach the lever that the cable pulls through the handhold hole on the left side of the tail cover. Using a long thin flat blade screwdriver you can push the end of the lever the cable is hooked into towards he right side of the bike and un-latch the seat....at least with my carbon fiber tail....I presume the stock plastic tail has the same opening...maybe not.
I took some phone photos. They came out like crap....but here they are. One shows the screwdriver blade pushing the lever. The other shows the hand hold opening in the tail section and the daylight where the seat latch is hiding.