Hi,
There isn’t really a way around this, the MC7304 only offers a sngle USB end point with AT command access which the Microtik then give the user access to for PPP dial up AT commands, etc. In normal applications which design an MC7304 in you are able to use other network interfaces that the unit enumerates to the system with which allows you to maintain AT command access to the unit (or use the QMI interface) but Microtik does not allow this.
Regards
Matt