You can store it inside the LH2 tank, but you'll need to use it completely before you run out of LH2 or it gets too hot. You might be able to inject it in a cold LH2 feed that doesn't pass by the cooling channels and injects directly into the combustion chamber so any N6 gets flushed into the chamber before the engine runs out of LH2. LH2+N6 needs to flow fast enough it doesn't heat up before it hits the chamber.

Still, one commenter mentioned this is too explosive to be used as an explosive. That kind of warns me against thinking too much about this.