George R.R. Martin has followed up on IDW’s announcement at Comic-Con with a detailed post about the comic, noting that it’ll be based on his revised script for the pilot rather than on the pilot itself, so character likenesses and the like will not be based on the rarely-seen pilot. Stefano Martino, an Italian artist who has worked with IDW previously on such things as their licensed Doctor Who comics, was hand-picked by Martin to handle visual chores, while Martin himself will adapt the teleplay to comic book form.
GRRM adds that if the series is a success, there could be more Doorways comics, beginning with his first draft of the pilot script (substantially different from what was produced, due to a setting which was so bleak that the studio asked it to be changed to something more hopeful) and then on through the six unproduced scripts (one of which was written by him), and then possibly on to original stories ... from other writers, handpicked by GRRM, of course, as he reiterates that his primary writing focus remains with A Song of Ice and Fire.