You know how you can make a Lua script to replace an element with another of your own making? Well, I have a script that I got from someone that makes MTOR, a VERY cool element, but it replaces ELEC and therefore breaks all ELEC saves. You should be able to make an element without replacing another.
The Lua API can only replace elements that already exist, but there are some elements that are still in the game, but they're disabled, You can look through the source for elements marked at /*FREE*/ there's about 5 or 6 of them, you just have to set them to enabled, menu to 1 and menusection to a valid menu.
Practically, if TPT's compiled before running, then it's pretty much immutable. Chances are that Simon can solve this, but for now use the placeholder element.