No, there is currently no support for extended keys.
Ok, thanks. Managed to handle arrows using zx+ extended codes (CSpect's "basic" mode). Observed a strange behaviour though: if I press say "up" and, while keeping it down, press "left", then release only "left" ("up" stays pressed) - seems like both bits for "5" and "7" are back to "released" (high) state instead of just "5". Works as expected on the hardware.