All Tibetan divination practices have specific requirements, ranging from lungs, to receiving empowerments to practicing in retreat prior to using them. However you can attempt using the Manjusri based divinations without these and see for yourself if you can pull it off. There is some chance that you might. Apart from the really esoteric systems, like mirror divination, etc., the principle behind most MO practices is simple - you have to have confidence while performing the practice, which should be strong enough to overcome the scattered dualistic mind, every time you do it. This confidence can come from an yidam, or from any other form of connection to your basic sanity. Anyone who can achieve this level of confidence can do successful divinations.
On another note, and with no intention to divert the topic, if you have trouble getting the necessary transmissions for one of the Tibetan systems, just learn Tarot, which is one of the most extensive divination systems ever designed and which surpasses 98% of the Tibetan systems in complexity and scope. In this regard THIS
is the book to get (two volumes).