Well, first of all, you really have to make sure that the ESC will work with a LiPo battery pack. If it will, then you have to match up the LiPo plug to the one that goes to the ESC.

There are some problems with this, though. First of all, the weight difference will most likely require you to re-locate the battery pack to meet the CG (Center of Gravity) of the plane.

You might be better off swapping out the motor/esc/battery pack to a matching set of LiPo and brushless ESC and matching motor.

CGr