It's actually very straight forward. Make sure you get the LS-40 01. It has the 5 pin adapter making it a direct swap. I don't think any of LS-40s come with an S bracket, so you will need to order that too.
The other thing you should do is make sure you have the lever oriented the right way before you screw it in. IIRC, Seimitsu levers have the 5-pin connector positioned 90 degrees different from the orientation used by the stock equipment in a MadCatz stick. It's easy to figure this out: plug in the connector to the LS-40, then connect the controller to your console. If only one direction works, unplug the connector, turn it over, and then plug it back in. Then just turn the lever in your hand until you find the correct orientation.