How do you replace the crank shaft in a front wheel drive car?

Remove the entire engine, strip it down to pretty well the block and start all over.

Replacing the crank shaft in any internal combustion is pretty much the same. It entails removing the engine, having machine work done on it, new bearings on the connecting rods, etc. It's not a job for a DIYer unless you have a lot of time and a good working knowledge of engines. The tolerances and very tight and specific.

The cylinders may need to be rehoned or even cut and opened up, new pistons and rings installed etc. It is not for the faint at heart!