To run a 2 cell LIPO there is no need to make any changes except to add a LVA or LVC to your battery. This is because a fully charged LIPO runs at 4.2V per cell, or 8.4V total for a 2 cell lipo. It actually sits real close to a charged 6 cell NIMH battery in voltage, so no change is needed.
LIFE is another story. Since it's max voltage is 3.6V per cell, you are getting very close to the danger zone to run a 3 cell LIFE battery. You are best running a 2 cell LIFE battery with a LVA/LVC attached. The LIFE battery has a good discharge profile so you wont see much of a voltage sag under load like you do with NIMH/NICD batteries.
Also, BUY A LVA OR LVC! They are cheap and will save your models. They can be used on tanks, cars, helis, quads, trucks, etc. It has been one of the most useful items ever since I started using lithium batteries. I shall do a LVA video sometime to show how great they really are.