You could achieve this using a CreationFilter, but it would be quite tricky. In a very simple case, where you know that your application is not using Application Styling and you know which Style the UltraToolbarsManager is going to use, then you could make assumptions about the color(s) and styling of the button and that would simplify things a bit. 

Based on your screen shot, which is apparently using Office2013 style, I whipped up a sample of how you might go about adding a single button to the header. If you wanted more than one button, or to dynamically change the button(s) at run-time, that would of course be a lot more complicated. 

My sample just uses a simple string as the context for the button and it creates a placeholder image using the first letter of the string. If you were going to do this in a real application, you would want an image with magenta in it and the magenta would be replaced by the ForeColor - which is what happens with all of the other system buttons in that area. 

Anyway, even this simple case was pretty complicated and required a lot of code. So please let me know if you have any questions. 

UltraToolbars_Header_Button.zip