Since Elder Joseph has not been made a saint, I don't think there are any published services for him. I have heard that some things have been written for him on the Holy Mountain.
Regardless, one could easily "guess" what his Apolytikion will be once published. As an ascetic, it should be in the third mode modeled after the prosomoion for ascetics. For now, just use the one for a similar father, St. Arsenios the Cappadocian, and replace the name:
Βίον ένθεον, καλώς ανύσας, σκεύος τίμιον του Παρακλήτου, ανεδείχθης θεοφόρε Αρσένιε, και των θαυμάτων την χάριν δεξάμενος, πάσι παρέχεις ταχείαν βοήθειαν, πάτερ Όσιε, Χριστόν τον Θεόν ικέτευε, δωρήσασθαι, ημίν το μέγα έλεος.