Changing the User Buttons

I have programed my cdj user buttons to do some great things (like one touch play of randomized lists chosen by keyword) but want to redo the look of the buttons to more accurately represent their function.

I understand how to use my graphics programs to change the user.bmp file and have been successful, except that I want to increase the width of the buttons (I know that the height has to stay at 16 pixals). What function tells CDJ to "cut" the user.bmp file where it does (after every 2 digits)? Can that be changed? Can I create buttons that are 16 pixals high but any length?

Thanks for any help you all can give.

Cheers