So, Bastards of Golarion has this interesting little trick:
Spoiler:
Dark Shifter (Su) (Bastards of Golarion pg. 9): The magus can expend 1 point from his arcane pool as a move action to change the target of an ongoing spell effect with the darkness descriptor within 60 feet. The new target must be within the spell’s range, using the magus’s level as the effective caster level for the purpose of determining the maximum range the effect can be moved from the magus. If the spell effect the magus is moving originated from another creature, the magus must succeed at a caster level check to reposition the effect (DC = 11 + the effect’s caster level). Failure wastes the magus’s move action, but does not expend the point from his arcane pool. The magus must be at least 6th level before selecting this arcana.
So, "The new target must be within the spell's range". So what happens if the spell has a range of "Touch"?
Looks like it means the new target must be within spell's range in relation to the magus. So within touch range of the magus. Seems like you should be able to move the spell to a rock and then throw it next turn.
The actual combo I had in mind was tagging enemies with Arcane Mark modified with Umbral Spell, stacking a few of those on my sword and inflicting them on an enemy with a move action.