You would either need to tweak the InventoryUpdate packet in both the game client and server or create a completely new packet.
I'm not sure if it would be possible to send so much data through the InventoryUpdate packet, though. I've read somewhere on the forum long ago that each packet has a defined size limit, which you cannot exceed.
default_npc was the one who wrote that, if memory serves me correctly. If that's the case, then you would need to somehow feed the data to the client cache, one way or another.
A better approach would be to create a new packet (I know that it is possible, but don't ask me how. If somebody knows how and is willing to share, would be much appreciated!) and send the info through this newly created packet.