But you don't have to use an IC to get the effect. The idea is that when the H-bridge pulls low, it pulls the source of the high side FET low, and you can tie one end of a cap to that, and charge the cap through a diode from the supply that runs the gate drive of the low side FET. Then you have a supply (the charge on the cap) to drive the gate. This works even if the H bridge doesn't pull low very often, IF the gate drive switch doesn't discharge the cap with a significant DC current. A modern MOSFET will hold its gate charge for an incredibly long time, if there are no leakage paths.
Or were you wanting to actually use the voltage multiplier output to _control_ the gate?? That doesn't see like a very good way to do it, since then the gate must be pulled down by a resistor (or some overly complicated circuit) to turn the high side off.
Cheers, Tom