[Ace]

Basically a small module with an OnUpdate() handler, that checks to see if certain keys are held down.

Code:

FlyHack = {}
lasttick = 0

function FlyHack.OnUpdateHandler( Event, ticks )
    if ( (ticks - lasttick) > 200 ) then
        lasttick = ticks
        
        --keys can be found here (convert from hex to decimal) - http://nehe.gamedev.net/article/msdn_virtualkey_codes/15009/
        if ( MeshManager:IsKeyPressed(038) ) then -- if holding down up key
            local ppos = Player.pos
            GameHacks:TeleportToXYZ(ppos.x, ppos.y + 5, ppos.z) -- fly up some predetermined value
        elseif (MeshManager:IsKeyPressed(040) ) then
            local ppos = Player.pos
            GameHacks:TeleportToXYZ(ppos.x, ppos.y - 5, ppos.z) -- fly down some predetermined value
        end
        
    end
end

function FlyHack.ModuleInit()
end

RegisterEventHandler("Gameloop.Update",FlyHack.OnUpdateHandler) -- the normal pulse from the gameloop
RegisterEventHandler("Module.Initalize",FlyHack.ModuleInit)

Something along those lines, not tested at all.