01 Stratus burning oil

When accelerating from a stop there is a lot a white smoke that comes out of the exhaust. It doesn't do it when I start it up. It is a 2.7 DOHC with about 115k miles.

White smoke usually denotes that you are burning a little bit of coolant, which means a failing head gasket. If the smoke has a bluish color to it and smells like oil, then the most common cultprit is your piston rings are wearing out.

I know for sure that it is not the headgasket. If it is the piston rings how much work is involve to replace them.

Quite a bit. You need to almost take the engine apart. The cylinder head needs to come off so you can take the pistons out. And the oil pan will need to come off so you can get to the connecting rod bolts to disconnect the pistons from the crankshaft.