There doesn't seem to be an answer for this anywhere on the internet, not for 1.4 at least. What do I add to the .lua file that will allow me to skip rerolling and set all stats to 18? This is for Icewind Dale EE, by the way.

I don't know how to do that but may I offer an alternative? Why don't you use EE Keeper? It should work for IWD:EE as well. That way, you will be able to change anything you want.