It is one of the simplest guitar mods ever!..
1/ Unscrew the existing Jaguar pickup
2/ Loosen or take off the strings
3/ Unscrew the pickguard
4/ Unscrew the three switch plate
5/ Heat up soldering iron, have a cup of tea
6/ The two wires coming from your jag pup one is HOT and goes to the switch point (take note of this point or mark it with a pen), the other wire is a GROUND wire going to the ground point on the plate.
7/ Unsolder these two wires off the switch plate and replace them with the Seymour Duncan (hot and ground were appropriate)
8/Put everything back together.
If you want to reinstall the 'claw', unsolder it from the old pickup and make sure you solder a jumper piece of solder to the ground wire on the new pickup.
The pickup cover is a different matter, i dont think it will fit over the SD pup without cutting the top section of the cover out.
Good luck!