HTML

<input id="hex" type="text">

Script

$('#hex')
	.keyboard({
		layout: 'custom',
		customLayout: {
			'default' : [
				'C D E F',
				'8 9 A B',
				'4 5 6 7',
				'0 1 2 3',
				'{bksp} {a} {c}'
			]
		},
		maxLength : 6,
		// Prevent keys not in the displayed keyboard from being typed in
		restrictInput : true,
		// include lower case characters (added v1.25.7)
		restrictInclude : 'a b c d e f',
		// don't use combos or A+E could become a ligature
		useCombos : false,
		// activate the "validate" callback function
		acceptValid : true,
		validate : function(keyboard, value, isClosing){
			// only make valid if input is 6 characters in length
			return value.length === 6;
		}
	})
	.addTyping();