Generally, a non-resident must acquire his licence through an outfitter, however, a non-resident may hunt with an immediate relative who is a hunter licenced to hunt moose in the same WMU. You can also apply in the resident moose draw, but you must submit the application and an affidavit in the applicable WMU office before the expiry of the draw period (May 31).
If you're unable to submit an appication in that manor, I believe you still need the affidavit to buy a resident licence, but I also believe you may party hunt with your brother, and participate in the kill of any adult animals his party may have.
I'd suggest that you contact the MNR office responsible for the WMU and get the info direct from the source.
If you know the WMU you plan to hunt, I can give you the phone number of the responsible MNR office - although your brother should have this info as well..