The dynamic text feature is not supported in current version. But calling 'update' method can also change the specify node's color.
var node = $('#tt').tree('find',...); // find a node
if (node){
if (node.checked){
node.text = '<span style="color:red">Text</span>';
} else {
node.text = 'Text';
}
$('#tt').tree('update', node);
}