well, this is how i would start; copy/paste the USA dozer code, and at the very top of the code where it says AmericaVehicleDozer, just change it to whatever you want. It will have its regular commandset, but this is irrelevant if it will be changed in the map inis.

Then make a button to build it, and add an entry into a factory/command center commandset for the button.

If you want more buttons than will fit in your dozer commandset, you'll have to make a upgrade for it to change commandsets. Look at the GLA worker to see how this works.

Also, i'm not exactly sure if the dozer is able to build units or not. If it can't build unit by default, you'll have to compare the code of a factory and the dozer to find out whats different.

As far as changing code via map inis, i'm not exactly sure how to do this. One of the other guys will hopefully reply to this topic and say how. There's probably tutorials/info out there explaining how to use map inis.