You don't have to. This spell replaces the worker with an advanced worker who can build any buildings you want it to (in the limit of 11 buildings, so it's like if the builder could build 2*11=22 buildings instead of 11). So all you need to do is customize the units, that's all.
Thanx IIILSDIII, I fixed it, I forgot to fix one trigger when I copied and pasted the ability from the map of my campaign I was currently working on to this demo map. It should be OK now.
