Defender Alcaraz, who signed from Wigan Athletic in July, has yet to make his debut for the Toffees, having undergone groin surgery in the summer.
Meanwhile, Pienaar has missed the last four matches with a hamstring complaint.
"Stevie has reacted really well to treatment and he is progressing extremely well," Martinez told reporters. "Antolin Alcaraz has had a very good period as well, so, all in all, those two have benefited enormously from this international break.
"We don't want to put a date on it. We are very much seeing their reaction and seeing how quickly they can take the workload on. In medical terms, they shouldn't be fit for Hull [on October 19], but I would not say they cannot make it.
"There's still a question mark over them but Steven is a litle bit ahead. It's been really positive to see them with big smiles and enjoying their work."
Everton currently sit seventh in the Premier League table with 12 points from seven games.