You'll have to fake it with an airship that looks like a flying Goku. Of course, there's a bit more to it than that.. but there's no need to reinvent the wheel, here's a quick link to a decent tutorial on the subject:

http://www.gamingw.net/tutorials/533

Of course, if anything needs explained further I'll help out. That tutorial only shows how to "push button to lift off" in a way. You can modify it to trigger on an item used instead of a button press by making a switch to the main common event.

The logic behind the flight thing works like this:

---------------------------------
Use item, sets switch

(PARALLEL PROCESS)

-- Hide character
-- Make "airship" (i.e. Flying Goku) appear on the same tile
as the character, and have character enter the airship, which then starts flying as airships tend to do

-- Pause the event. If character hits enter to land, continue past this point, otherwise the character remains in flight

-- Airship lands because you hit enter
-- Hide the airship and make the main character appear again

(Add these at the end of the parallel process)

-- TURN OFF THE SWITCH
-- Throw the airship somewhere that you can't hop on it
------------------------------------

The red parts are my suggested additions to the logic.

With the item, you'll end up with an invisible airship that you can hop right into without using the item. You'll want to move the airship away, preferably into the ocean, so you can't just hit enter or space again to lift off in your invisible airship.