As a rule, you can't book codeshare tickets with miles, so any award ticket on another airline is booked as that airline's marketed and operated flights. AAdvantage's partnership with Interjet is described here:
https://www.aa.com/i18n/AAdvantage/e...s/interjet.jsp

According to this page, miles can be only earned on AA-coded Interjet flights, not redeemed, so you're out of luck in that respect. However, using miles to book your ticket to MEX and paying cash for the flights to OAX (whether on Interjet, Volaris, or another carrier) may be cost-effective.