Officially no, but some posts suggest you can do it with the right Y-connectors
http://forum.mikrotik.com/t/problem-with-mount-point/94/1
http://forum.mikrotik.com/t/map-lite-usb-lte-modem-using-portable-mobile-battery/110638/1
Watch out for the overall current draw though. The mAP has a maximum potential draw of 1A at 5V, and a 3G modem will consume a fair chunk too.