Basic script to create a template for a 4 panel comic page. All Panels are the same size based on page size and 2X2 layout with a 50 pixel border between them. Will do some more work on the script later to make it more flexible.
If you want the panels to be clear so you can slide you images in behind them then remove the ; from the start of line 39
; (gimp-edit-clear layer)
once installed you can find the script on the filter menu (should be down near the bottom).