Custom Hopper Event

Is there a way to say place a obsidian block and have a hopper facing to it input the obsidian's block inventory with items? For example with vanilla Minecraft a hopper facing a chest inputs items into the chest?
Thanks!

EDIT: I am have decided to power a hopper to make them push items... This will make it easier so I just grab the items and have a scheduler give them a delay to put them into the target. How can I get when the hopper is powered? I've tried a BlockRedstoneEvent but that does get when a block is powered just when redstone is?