If you are even slightly able-bodied, walk (especially prior to such a long flight). The airport is essentially a ring, so even if you go the wrong way, you'll end up in the right place. When you leave the secured area of T-1, make a left and follow the signs to the int'l terminal. The part that says Main Hall will have your check-in counter, and there will be electronic signs at the end of each row that will tell you which row your airline will be at that day. After you check in (and do so, even if you've received a BP @ATL) you'll be directed to the security checkpoint for the G gates.