Some basic scripting aid.

I was trying to test one theory I had about poor stock AI, and I need some help in scripting.

My theory is that AI doesn't build enough colonyships. This causes it to fall behind.
I found the script_AI:construction.txt from the scripting tools.
At the end of this file AI decides which ship to build.

I was hoping to let it run normally, but at the very end check how many colony ships the empire has (ready on in queue), and if the number is less then defined value(5?), then the ship type is replaced by a colony ship.

However, while I am able to interpret the script to some extent, I have no idea how to do the following.
Can someone give me a ready script part to insert in the file, or hints? I'd like to test my theory, and see if such easy way would make stock AI better.