Just put it in normally, bring it back a small way and let the nozzle rest on the top of the pipe. Neither my wife or myself have ever had a problem at any pump.
The formula is HP (horsepower)=(RPM*TOURQUE(Ib/ft))/5250
For the IS200
at maximum torque hp = (4600 * 144) /5250
= 126bhp
I don't know the torque figure at 6200 rpm so let's do it the other way around
at maximum power torque = (hp * 5250) / 6200
= 130 lb/ft
I think the 5250 should really be 5252 to be totally accurate.
What output does the PSU give? If the PC runs only on 5v then the PSU should be able to give a regulated supply even with the 12v input going up and down.