Here you are. Hope it works :)
function onStepIn(cid, item, position, lastPosition, fromPosition, toPosition, actor)
local spellbook = 6120
local levReq = 20
if(getPlayerSlotItem(cid, CONST_SLOT_RIGHT).itemid == spellbook or getPlayerSlotItem(cid, CONST_SLOT_LEFT).itemid == spellbook) then...