Yes I’ll add a quick tutorial on this in the near future and will add it to the Tutorial section of the site.
Until then, all you would need to do is go into your functions.php file and adjust this –
// Add support for custom header
add_theme_support( 'genesis-custom-header', array(
'width' => 1152,
'height' => 120
) );
Make sure and find out the exact size of your image first and add it to your functions file. Then after you do this the header uploader will automatically upload your image without the need to crop.