Slave cylinders are simplicity itself, or should be.
Remove it from the engine, clean it up if necessary, then use the master cylinder to pump out the slave cylinder. Be prepared to catch the hydraulic fluid!
Some slave cylinders have internal springs.
Some use standard o-ring seals. If an o-ring, make sure you replace it with a Viton one - usually green. Buna-n will swell in hydraulic fluid.