The total gate charge is 129nC max which is what I assume you might use to calculate the current needed?
Coulombs (C) are in the units of Amp.seconds, so if you multiply 129nA.s by 400 Hz (1/s) you get 52uA. If the 9V battery has a capacity of 400mA.Hr, then it will last for around 11 months, if it were just charging and discharging the Gate capacitance. There will be some other losses in the driver which will reduce this, probably by a fair amount; though it will definitely be in excess of 1hr by a few orders of magnitude.
I also like dougy83's solution below, but it seems a little more complex, it will be something to consider as the project progresses.
It can be simplified, though at the moment it has pretty good performance and will take up much less space than your 9V battery and will be cheaper.
John, hang on a sec, looking over the datasheet this AOT410L will not work...after looking at the SOA I could only get about 5A at 80Vds. The devil is in the details... Do you know of a cheap mosfet that would handle 80Vds with 150A continous or am I dreaming? Might I have to double up?
Figure 9 is for a MOSFET that is operating in its linear region. From what I understand, you want to drive your MOSFET such that it is either fully on or fully off, right? In this case you should be looking at the details in figures 1 & 2. You are probably dreaming if you want to get 150A through it continuously, as you'd have to dissipate ~170W of power. This would need a large heatsink and fan. If you double up, each MOSFET dissipates a quarter of the original power, so you could get away with half the original heatsink.
You should realise, if you're switching at 400Hz, then the MOSFETs aren't running continuously.