I had the similar question in the EasyList thread.
When you use a non default color (pattern) for a button (like a red button for stop), it drops it's Maemo look and feel and falls back to a basic Qt one. Then it's better to apply the new look and feel to all the buttons, and not end up with a mix of buttons.
If someone knows a way to prevent loosing the Maemo look and feel in that case, let me know...

With the right stylesheet, perhaps the buttons can look almost identical to the Maemo one again.
And one could search for theme colors and try to apply them to the buttons that should have the default theme color.

So the easy answer is no, the more complex one is... at least almost

Edit: had a closer look at it. The theme buttons are actually PNG images. That should be the reason why you can't change their color. And will make it almost impossible to create identical buttons in different colors.