Is it possible to remove crankshaft pulley (dynamic balancer) with the engine still in the car.
TJ Magna 3.5 AWD

It certainly is - best you download the workshop manual at: http://www.lisho.net/?page_id=3
This will make it much simpler in your mind.

Yep - jack up the front drivers side wheel, remove it and the splash guard, and there it is! 24 mm socket and breaker bar needed.

Yep, replaced mine with a lighted stainless stell one with the engine still in.

tip: leave the crank bolt in by a few turns , so when the pulley comes off it doesnt drop on the ground. ouch