Not a very difficult task, if you have the right tools. You'll need a good table vise with anvil surface, pin punch, and pointed staking punch.
Drift out the bolt stop pivot pin (shown with arrow) with the pin punch. This may take some force as the ends of this pin are heavily staked into the mainspring housing. After replacing old bolt stop be sure to stake heavy dimples in both ends of the pivot pin to prevent walking with the pointed staking punch. Otherwise you may have a situation where you cannot disassemble the pistol because the pin has walked out of the mainspring housing and is preventing the housing from being removed from the frame.
I just grind the rivet staked side off with a Dreml, being careful to just grind the rivet. Drive the rivet out and replace the pin and stake in place! JMHO