How do I boost charge a dead 3.7v li-ion battery?
You can't "boost charge" a Li-Ion battery. When you say it is "dead", I assume it doesn't deliver any voltage/current. There could be two scenarios of what has happened.


The battery has a built-in protection circuit. When the (internal) cell voltage drops below certain threshold (like 2.5-2.9V), the circutrty disables the battery output.
The cell gets drained to actual zero due to self-dicharge parasitics. Then it is formally "dead".


There is a third scenario when the cell went dead after a catastrophic overdischarge (short), which destroyed internal conductors. I assume this is not the case here.

In first two cases there is a chance for recovery. You should apply a very modest "precharge" current (say, 100 mA). If the cell is just overdischarged and is shut down due to protection, it will quickly gain some voltage above the cut-off thershold, and the protection circuit will disengage. Then you charge the battery using normal means of your device.

If the cell has no protection and is dead by electrochemical depletion, there is still a chance that it will come back to life. However, studies show that the process of recovery is unpredictable, and in no case the cell can be restored to its original capacity. The result can be anywhere. See also some relevant discussion here.