Change smilies to custom theme directory

I have my own custom smilies. I want to change the directory where WordPress finds the smilies to a directory in my theme files using my theme’s functions.php template.

I have located the function in the core files where WordPress finds the function

function translate_smiley($smiley) {
	global $wpsmiliestrans;

	if (count($smiley) == 0) {
		return '';
	}

	$siteurl = get_option( 'siteurl' );

	$smiley = trim(reset($smiley));
	$img = $wpsmiliestrans[$smiley];
	$smiley_masked = esc_attr($smiley);

	$srcurl = apply_filters('smilies_src', "$siteurl/wp-includes/images/smilies/$img", $img, $siteurl);

	return " <img src='$srcurl' alt='$smiley_masked' class='wp-smiley' /> ";
}

So far all of my attempts at rudimentary custom theme function writing have failed. Any suggestions would be appreciated.

Adam