Butter alternative for making breads
Butter flavored shortening and a touch of water (because butter has water in it too).  The key thing here is that you have a have a solid fat because you're beating air bubbles into the butter during the creaming process.  These bubbles are needed for the bread to properly rise during baking.

The browning process may be an issue though - shortening has no protein.  You're after an umami flavor from the Malliard reaction ...  it may be difficult to add that because of the lack of protein.  A pinch of MSG maybe, for the umami?