theres 2-3 different methods. some involve treatment with chemicals such as colliadial silver that forces a true female plant to produce male pollen, but with female DNA, not hermie.
another but much more risky (of producing a hermie) technique is to over ripen your buds in the hope that some male flowers (bananas) will appear. pollen is collected and then used to pollinate the same mother it was retrieved from. this is a 50-50 gamble, and theres no way of telling untill you flower the plants grown from these seeds