F on domestic flight from international terminal?

[nufnuf]

Is it possible to book in First class on domestic flights that leave from the international terminals in Australia? It should be possible but I have yet to find anywhere that will let you check/book availibility on these flights. Anyone had any success or is it not possible to book these fares?

 

[aus_flyer]

F is not sold.
3 class planes are sold as 2 class, and some J passengers get to sit in F.