Hmmm, a CD4007 could work - power it from 12V with /PGM input on pin 6 to level shift it with a pullup on pin 8 for the N-MOSFET and pin 13 tied to Vdd to disable the P-MOSFET, then use the inverter to restore the signal polarity and the remaining uncommitted pair of MOSFETs (pins 1-5) to replace Q1 and Q6 above. However the DS2502 datasheet calls for a 10mA programming pulse supply, and the CD4007 only guarantees 0.55mA (@10V Vdd, 25°C), so it would need the P-MOSFET boosted by connecting a PNP transistor base to its source, emitter to the rail and collector to the DS2502 data pin.
It would still need the Schottky clamp and series resistor R. The purpose of R is to limit current in the Schottky clamp to prevent the 3.3V rail glitching excessively (fit a 0.01uF decoupling cap on the 3.3V rail right next to its cathode), and to prevent its Vf drop exceeding the permissible excursion of the MCU's I/O pin above its Vdd rail - typically 0.3V. Try a BAT54 or similar diode and for R use 100R to start with, which should cause negligible voltage drop when either the MCU or the DS2502 is pulling the bus low. Personally, I'd prototype the DS2502 bus driver without the MCU connected, applying debounced control signals manually via ordinary logic gates, and if you observe an excessive spike on the MCU side of the bus, try a beefier Schottky diode, as increasing the resistor too much will compromise your logic levels. I know a 1N5817 will clamp it OK at less than 0.3V above the rail, but its leakage current may be objectionable.