Quite easy with the actions I use. They take remington type triggers. So if it's a modern type target action it should have a "trigger hanger" which is held in place by two cap screws. So you make the trigger slot big enough so the trigger will drop out after the 2 screws are removed.
I found a pic of an action with the trigger attached to the trigger hanger.
For the actions with pins, just drill holes so you can knock out the pins.
With a hanger I can remove the trigger in about 60 seconds.
G'day All,
most custom actions, such as the Stolles, Hall, Bat etc have a trigger hanger (adapter) that bolts to the underside of the action, so you can simply unbolt the trigger/hanger assembly from underneath and then swap the trigger easily at the bench/car bonnet without struggling with the whole rifle.
Makes glue-ins a whole lot easier than with a Rem action and the 2 pins