@Norvin Actually there might be a way of making it easier and safer...I need to do some tests later. My thinking is...with a cold machine, switch on, but turn off all the heaters...group, boilers..the lot. Then everything is cold.
Use a rubber blanking disk...pull down lever and with an insulated screwdriver, adjust the stat to the pump pressure you want. Probably working up, rather than down (cost you can't release the pressure).
For safety you should switch the machine on/off at the mains before each adjustment...and
not just adjust it with the pump running like I would, to avoid the massive ballache..Even though the screw in the pressurestat is plastic...you never know, perhaps the manufacturer might change to a metal one (hence the insulated screwdriver).
Switch machine off and with a teatowel around the group, gently unlock it a little until the pressure leaks out. The water is cold, so the teatowel is just so you don't get a Mrs pimple popper soaking. With the machine off and boiler cold, the pump won't run to refill the group and nothing will get force out of the boiler.
Finally control the lever firmly as you move it back to the uncocked position.
Should work!