I think custom scripts in MP is already possible, but due to the nature of peer to peer play, syncing those actions is the real problem and forces you to become something of a multiplayer coder. When we go the Standalone Multiplayer App, we can address this subject and maybe make cross-player scripting easier for all.
PC SPECS: Windows 8.1 Pro 64-bit, Intel Core i7-5930K (PASSMARK:13645), NVIDIA Geforce GTX 980 GPU (PASSMARK:9762) , 32GB RAM