add this javascript to your browser as a link and click it to enable keyinput throu the web ui remote. Use wasd, enter and q to navigate

xbmc_remote_keys.js

$(document).keypress(function(e) {
	var element;
	switch (e.keyCode) {
		case 119: // W
			element = $('#up');
			break;
		case 97: // A
			element = $('#left');
			break;
		case 115: // S
			element = $('#down');
			break;
		case 100: // D
			element = $('#right');
			break;
		case 13: // enter
			element = $('#ok');
			break;
		case 113: // Q
			element = $('#back');
			break;
		case 49: // 1
			element = $('#volumedown');
			break;
		case 50: // 2
			element = $('#volumeup');
			break;
		default:
			console.log("No function for key " + e.keyCode);
	}
	if(element) {
		element.click();
	}
});