MonoX is using repository pattern in combination with LLBLGen Pro ORM for data access. If LLBLGen doesn't suits you, for your custom projects you can use whatever technology you want e.g. ADO.NET, NHibernate, etc. Although I'd recommend the LLBLGen Pro because it is very flexible.
What exactly do you want to create (custom module - if so give us more information on the module) so we can help you a bit more ?